Jag tycker att han tyckte om Tyrion men jag tror inte att hans främsta motiv för att slåss var hans kärlek till Tyrion.
Hela anledningen till att han kom till kungens landning var att ta reda på vad som hände med sin syster, som gav ordern och om berget gjorde vad Oberyn tyckte att han gjorde.
Tyrion Lannister: Why did you come to King's Landing, Prince Oberyn?
Oberyn Martell: I was invited to the royal wedding.
Tyrion Lannister: I thought we were speaking truth.
Oberyn Martell: [pause] The last time I was in the capital was many years ago. Another wedding. My sister Elia and Rhaegar Targaryen, the Last Dragon. My sister loved him. She bore his children. Swaddled them, rocked them, fed them at her own breast. Elia wouldn't let the wet nurse touch them. And beautiful, noble Rhaegar Targaryen... left her for another woman. That started a war, and the war ended right here, when your father's army took the city.
Tyrion Lannister: It wasn't actually...
Oberyn Martell: They butchered those children. My nephew and niece. Carved them up and wrapped them in Lannister cloaks. And my sister. You know what they did to her?
[Tyrion has been staring at the ground uncomfortably for some time; Oberyn lifts his chin with a finger]
Oberyn Martell: I'm asking you a question.
Tyrion Lannister: I've heard rumors.
Oberyn Martell: [chuckles] So have I. The one I keep hearing is that Gregor Clegane, the Mountain, raped Elia and split her in half with his greatsword.
Tyrion Lannister: I wasn't there. I don't know what...
Oberyn Martell: If the Mountain killed my sister, your father gave the order. [pause]
Oberyn Martell: Tell your father I'm here. And tell him the Lannisters aren't the only ones who pay their debts.
[Oberyn walks away]
Spoilers om kampen:
Throughout the fight scene he is constantly shouting "Elia Martell of Dorne, you raped her, you murdered her. You killed her children." This is aimed at the Mountain and is also for the crowd. He also looks to Tywin when he says "Who gave you the orders?"
Kampresultatet visas i denna spoiler:
He is so obsessed with getting the Mountain to admit to what he has done that he eventually loses the fight because of this.
Sammanfattningsvis var Oberyns anledningar att slåss framförallt sin egen för sin stolthet och för hans syster och för Martells hus, men han tyckte också om Tyrion. Möjligheten att bekämpa berget uppstod och tydligt grep han det.