TL; DR: Eftersom Luke är en Jedi och Leia inte är.

Första ordningen är dock ivriga att döda båda syskonen - och i The Force Awakens kommer de faktiskt mycket närmare att döda Leia än att döda Luke.

Obs! Kursiv i följande citat finns i originalet; fet är min.

Vad har första ordern planerat för Leia?

De tänker döda henne, tillsammans med resten av motståndet. Hon är deras fiende. Men Luke utgör ett annat, eventuellt större långsiktigt hot. De använder Starkiller för att förstöra sätet för den nya republikens regering i Hosnian System, sedan rikta den till D'Qar, motståndets huvudkontor - vilket är där Leia råkar vara. Om denna attack hade lyckats skulle Leia ha dött.

Varför fokuserar första beställningen särskilt på Luke?

Eftersom han är en Jedi. Leia kunde ha varit en Jedi , men blev inte en. Om Leia överlever men Luke dör, är Leia ett mindre hot (åtminstone när det gäller Force potential), för att hon bara är en otränad kraftkänslig. Luke är en utbildad Jedi, så om han överlever, kan han bygga om Jedi-ordern. Leia kan inte, för att hon inte vet mycket om hur Jedi är.

Kan Leia till och med bli en Jedi vid denna tidpunkt?

Vi vet inte, men hon är väl över den primära åldern för att börja Jedi träning. I Force Awakens är hon förmodligen ungefär 50 år gammal.

Under den gamla republiken, när Jedi-ordern gick stark, började barnen träna när de var småbarn . Även Anakin, som var 9 år gammal när han träffade Qui-Gon och Obi-Wan, ansågs ursprungligen vara "för gammal" för att börja träna:

QUI-GON: I'm afraid not. Had he been born in the Republic, we would have identified him early, and he would have become Jedi, no doubt... he has the way. But it's too late for him now, he's too old.

...

OBI-WAN: The boy will not pass the Council's tests, Master, and you know it. He is far too old.

...

MACE WINDU: He is too old. There is already too much anger in him.

De utbildade Anakin trots dessa reservationer, och vad hände? Han blev ond, gick med i Sith, hjälpte till att döda Mace Windu, slaktade alla ungarna, hjälpte Palpatine att jaga den andra Jedi och etablerade sig som den näst värsta personen som någonsin levt.

I episod V, när Yoda berättar för Obi-Wan att, om Luke misslyckas, kan de vända sig till Leia, Luke och Leia är i deras tidiga tjugoårsåldern. Yoda är tveksam att träna Luke först för just denna anledning:

Yoda: He is too old. Yes. Too old to begin the training.

Yoda tränade honom ändå, och vad hände? Han åsidosatte Yoda och Obi-Wans grunder för att motstå striden att rädda Han och Leia från Cloud City, förlorade en hand, lämnade sin träning ofullständig, ignorerade Obi-Wans råd att han behövde döda Vader (även om den delen fungerade för det bästa ), nästan föll till Mörksidan, överlevde bara för att Vader tog synd på honom, satte upp en Jedi-akademi av sorter, såg sin stjärna elev (och brorson) döda alla andra studenter, övergav kraftens väg och gick in i gömmer sig.

Historiens moral: När folk börjar träna för sent, leder det ofta till problem.

Vad har Luke lärt sig Leia?

Inte mycket. För det mesta hur man mediterar och rensar hennes sinne:

The room is white and mostly empty. The walls are padded. The windows are many, and the sunlight streaming in is bold and bright.

The only things in this room are Leia and a potted plant.

The plant is a sapling of the sanctuary trees of Endor, though some call it a serpent’s puzzle, named so after the way the dark branches weave together in a kind of organic knotwork.

She grew it from a seed— a small knobby acorn given to her by the little Ewok known as Wicket. She grew the plant in a pot of Chandrilan soil, and to her shock and delight, it took.

It has become a focus of her meditations, as suggested by Luke. She decided, after storming out of the meeting room, that it was best to come here. Best for her to focus on something that wasn’t the state of the galaxy, or the nascent New Republic, or that nagging feeling in the deep of her middle that Mon has betrayed her in some small but significant way.

She sits with it in the middle of the room.

She clears her mind.

And then she tries to feel the tree.

She does this at least once a day.

Leia has never felt the tree.

Not for lack of trying! She sits here. She empties herself of breath, and then she tries to free herself of thought. Just like Luke taught her to. That part works fine most of the time. But he said it was possible to feel the lifeforce of things with the Force...

Luke continues to swear that, with time, she will come to feel the Force just as he does. He explained that it was how she felt his pain back during Cloud City— him hanging there, wearied and beaten and about to fall into the roiling clouds below. He said he’d teach her.

And he did teach her. Some things, at least.

Then? He left.

Just like Han left.

Luke...
- Star Wars: Aftermath: Life Debt

...

After a slow exhale, Leia says: “My brother taught me to center myself. To be mindful of what I’m feeling— a cup to be filled up, he says.”
- Star Wars: Aftermath: Life Debt

Varför satsade Leia inte på att bli Jedi?

Vi vet inte alla orsaker, men några nämns.

En del av anledningarna avslöjas i två kanoniska romaner - Efterdyning: Livsskuld , satt i 4-5 ABY, ungefär ett år efter Endor, en d Bloodline satt i 30 ABY, ungefär 26 år efter slaget vid Endor.

“Did you never consider following in your brother’s path and becoming a Jedi?”

Leia found herself caught short. “Why do you ask?”

“They say on my world that the Force sometimes runs strong in certain families.”

So much of the lore of the Jedi had been lost— but on Gatalenta, the old religion had remained strong. History had become legend, but some of the legends were still told. Gatalenta had been one of Luke’s first destinations when he began his research into the Jedi Knights of old. Tai-Lin continued, “If that is true, then you might have the potential, just like your brother.”

And my son, she thought but did not say.

“If you have that ability, then I cannot imagine why you would not become a Jedi as well,” Tai-Lin finished. “Surely I’ve known few people who would make a finer make a finer Jedi Knight than you.”

Leia inclined her head in gratitude for the compliment, but she could not answer right away, because she could not tell the full truth1. The Force was too important a subject to be shared lightly, even with Tai-Lin, her ally and friend. Her safe, sensible, and, as far as it went, honest reply: “My duty has always been here, in the work of creating a new and better government.”
- Star Wars: Bloodline

...

She swore to [Luke] that she just doesn’t have it. It being that mystical, intangible power that her brother possesses and (this thought comes with a set of chills grappling up her spine) that her father— her birth father— possessed, too.
- Star Wars: Aftermath: Life Debt

...

Luke said those strong instincts of hers served as proof of the Force, evidence that it was working through her all the time. Maybe he was right. But Leia believed just as much in her experience and her common sense.
- Star Wars: Bloodline

...

...Luke Skywalker, too, but this detail was nearly irrelevant to Lady Carise. Skywalker had been so long away on his strange quest for the lore of the Jedi that he no longer had much influence outside his own acolytes. He was a figure of myth more than one of flesh and blood...

"Princess Leia spoke of her brother, the famous Luke Skywalker, who has been little seen in the public sphere for many years now."...

“Since the Rebellion, Skywalker has lived a private life. He has asked no more of the New Republic than any of its other citizens, nor have we just cause to ask more of him than the substantial service he has already given."
- Star Wars: Bloodline

...

“That tracks. Two heroes of the Battle of Endor, and I haven’t seen Solo around here in months. Skywalker for even longer.”
- Star Wars: Aftermath: Life Debt

Således valde Leia inte att träna som Jedi eftersom:

• Hon var inte övertygad om att hon kunde vara en Jedi och tvivlade på sin Force-potential

• Hon var inte säker på att hon borde vara en Jedi, eftersom Vader var hennes pappa 2

• Hon kände att hon var bättre lämpad för en politisk ledarroll och blev sålunda en senator i New Republic.

• Luke försvann strax efter slaget vid Endor för att hitta Jedi gamla artefakter och platser. Han återvände kort för att ta Ben Solo på som student och lämnade sedan igen för att träna sina ungar. Efter att Ben vände sig mot Mörksidan och dödade de andra ungarna, gick Luke i att gömma sig på Ahch-To, och hans plats avslöjades inte till slutet av The Force Awakens .

Anmärkningar:

1 dvs den Vader var hennes pappa och det gjorde henne försiktig för att bli Jedi av någon anledning

2 Hon förklarar aldrig uttryckligen varför hon inte tillämpar denna resonemang mot Luke, eftersom Luke också är Vader barn, men det kan ha något att göra med att Luke, till skillnad från Leia, bevittnade Fars förlossning förstahand:

As always when Leia thought about this, she called upon what Luke had told her of their father’s last hours. He had renounced darkness, saved Luke, and become Anakin Skywalker again. Whenever Luke told the story, a beatific smile lit up his face; his memories of that event gave him a level of comfort and even joy that sustained him. Those were memories Leia couldn’t share...

Whenever she’d talked with Luke about their birth father, this was the part where he’d refuse to use the name Darth Vader. He was Anakin Skywalker when he fell in love with our mother, Luke would say, taking her hand gently in his. And he became Anakin Skywalker again in the last hour of his life. He came back from the dark side, Leia. They said it could never be done, but our father did it. He made that journey because of his love for us.

Leia believed Luke. She could feel that truth within him. But it was difficult for her to find solace in this the way Luke did. How could Vader torture her without mercy if he had that good inside? He’d still had the power to make the right choice, but had instead forced her to suffer...

Think of your conversation with Casterfo as practice, she told herself. One day she would have to reveal all this to her son. The truth of Vader’s identity had shattered her; she could not imagine what it might mean to Ben. At least Luke could tell Ben the most important part— that Vader had, in the end, been redeemed. Anakin Skywalker had returned; the dark side had been defeated by the light.

Leia knew this. She believed it. But she still did not understand it.
- Star Wars: Bloodline