Well there's no exact indication he was actually in line. My headcanon was always, giving his character, that he thought he was going to get married to Midna and something changed that and so the throne slipped out of his reach. I think if he was actually her elder brother (um, assuming the Twili use 'normal' ascension rules. XD) he'd have been able to do more with the mirror than he did.
Dwaaa! It's okay ; x ; / //pats head I spoil games for myself anyway, I already know how the game ends because I was researching Link and it's just kind of was read OTL I would love to see it for myself though, but not through youtube I wanna finish the game myself ; 7 ; <333