I mean, while some players may not like his conduct, no one in the narrative has any issues with him, no more so than poking fun at his expense, like Thancred's "conquests" Alph's inability to not be in charge or Alisase's act first, think later mentality. As for the cave scene, I'm not sure what you mean, was it his little "show" in recreating our first meeting? Because if so, it's hardly the first time a character has taken some time while we're on the clock, cleaning Y'shtola's room, baking bread and entertaining children come to mind off the top of my head, so I'll give him his 60 seconds. If it was him thanking us for brining him, then I'm not sure what to tell you, it wasn't just like he's tagging along, he was useful on the venture given his knowledge and blood so I'm really unsure what he did wrong there.
As for not being the Exarch, that's the point, because he isn't, the man himself, Urianger and Beq Lugg all said they had no idea what would happen to him when he merged with his younger self, he isn't the Exarch anymore, nor is he the young Graha, he's a mixture of the both and he's trying to find his feet as whoever that is and they said this several times before and after it happened so not sure where the "bait and switch" happened.
To your "predator" point... not even sure where to begin with this one, him having a huge admiration for the PC hardly makes him a predator he's also done a horrid job of getting near us given two of his three plans ended in his own death and he got lucky that he in fact not only didn't die but made it back to the source in possession of his time in the prevented timeline and first, he did not ask for a spot on the team, he was offered one by everyone else and so far he's pulled his weight when out on missions with us, he's never just "been there" for the sake of it. He also makes no effort to stick with us once we out in the field, either suggesting we split up depending on who can do what best or if it's suggested by someone else agreeing with zero complaints.
Finally Graha is probably the last character who could be described as having "no regard for people beyond his own needs and wants" Ignoring all he did as the Exarch, all he's done since getting to the Source is help, asking how he can contribute.