I have thoughts on him. Let me tell you about them (spoiler alerts for the first two games).
I think I’m one of the few people who actually likes this guy. My girlfriend, who introduced me to Golden Sun, is also a fan, so that influenced me, but it surprises me that the prevailing attitude towards him is ‘omg what a jerk’. Because…okay, he kind of is one. But I don’t know if I’d really call him a villain, since I can’t think of any occasion when he actually causes harm to anyone. Sure, he says lots of things that annoy people - disowning the Mercury Clan, saying he would’ve ‘borrowed’ Piers’ ship, introducing Karst and Agiato as added pressure to Felix’s team. But not all of his actions are that bad. For example…
-At Mercury Lighthouse, he rescues Saturos from Isaac’s party
-At Venus Lighthouse, he fends off the guards to let Jenna and Kraden escape
-At Jupiter Lighthouse, he refuses to help Karst and Agiato (who are being asshats). He heals Felix’s team, then later drags the Proxians away before any of them can kill each other
As for trying to grab the Golden Sun’s power, why not? Nobody else was going after it, and it was the by-product of a positive event - it’s not like he’d been drinking the blood of innocents in order to get it. Sure, it was sneaky, and in a way he was leeching off the hard work of others, but if I was in that situation I’m pretty sure I’d go for it too. And it’s not like he seemed to have any evil, world-conquering intentions (okay so he wanted to destroy Vale, but it was deserted and doomed anyway, no big deal there).
I haven’t played Dark Dawn, so I don’t know if he gets worse in that (I do own a copy of Dark Dawn, but can’t play it because my DS is broken, and I’m having issues with emulators). But in the first two games, I don’t see what’s so terrible about him. He’s a smartass and a leech, but doesn’t lie and act like he’s BFFs with all his temporary allies - so while he’s clearly not the nicest guy ever, I do find myself liking him. He’s interesting, if nothing else.
It’s hard to get his characterisation right in fanfic, though :c