Merrill is a weird character for me.
There aren’t a lot of party members in Dragon Age 2 whose personalities are actually appealing. Varric, I guess, is likeable from the start, but Aveline, Fenris, Sebastian, Bethany, and Isabela don’t have much charisma going for them. What personality they have tends to be either faintly annoying (Bethany’s resentfulness), cliched (Fenris’s brooding), or both (Isabela’s self-interest). Despite that, though, they’re all actually pretty decent characters, with enough depth and core beliefs and behaviors that they come out as positive in the end. Meanwhile, Carver is a pill AND doesn’t have any worthwhile character quality to make up for it, and Anders has the personality of a close-minded jerk and turns out to be even more of a thoughtless asswipe than he comes off as.
But then there’s Merrill. Merrill's is actually an enjoyable, appealing personality. She’s cheerful and flighty, with a naivete that’s actually charming (most naive RPG characters come off as forced and/or just really dumb) and a generally nice demeanor. Aside from Varric, Merrill is the character who consistently makes party banter engaging. I like hearing from her.
Here’s what makes her weird, though: Merrill’s a terrible, selfish person and I actually really hate her.
See, Merrill’s actual character development is that of a careless, obsessed fool who toys with forces that everyone knows have a long history of being dangerous. She’s so single-mindedly focused on her goals that she consorts with a demon and is easily manipulated into doing its bidding, eventually leading to a point where, if not for the intervention and sacrifice of an innocent third party, Merrill would have found herself possessed by the demon that she had stupidly put her faith in despite the warnings of those around her.
I mean, think about this--you have a character who makes bargains with demonic forces, who arrogantly and mistakenly thinks that she possesses the ability to control that demon, and is tricked the whole time into doing the demon’s bidding, all of which leads to the event where the demon is ready to betray its plaything and reveal its true intentions. Most of the time, that character I've just described is an out and out villain in an RPG story. I mean, just how many RPG villains have we seen that do the exact same kind of shit that Merrill does? Gaidel from Arc the Lad 2, the Drow queen in the Neverwinter Nights 1 Hordes of the Underdark expansion, the many people indoctrinated by the Reapers in Mass Effect, and so on and so forth; there are plenty of examples. The only difference between Merrill and your average misguided, egotistical villain is that, as I mentioned, she never has to pay the price for her stupidity. Marethari, the leader of the elves in the area and the one who has been telling Merrill to drop this obsession since the beginning because of its danger, takes Merrill’s rightful punishment onto herself. I suppose it’s not right to resent Merrill on this point since Marethari does this without Merrill having any choice in the matter...but then, the punishment is only coming because Merrill made her choice, for years, to ignore Marethari’s wisdom, not to mention basic common sense, so I still count it against Merrill all the same.
So, Merrill is quite a unique character for me. On the one hand, she comes off like someone I like--sweet, charming, friendly, and caring. On the other hand, she’s an overconfident, obsessed fool dabbling in obviously dangerous matters and ignoring the warnings of someone who cares for her well-being, eventually getting that person killed when the obvious consequences of her careless actions come to pass. I certainly can’t think of any other RPG character I’ve seen who I instinctively want to like, but can’t because underneath a sincerely likable personality they’re actually a major asshole. I don’t know whether this makes Merrill a well-written character or not, but it does make her a unique one.