IC, Narissa sees Alister as her greatest student. He was her first success, when it came to training a youth up for combat, and (though he has some areas that could be refined) he turned into a damn fine fighter. In some ways, she sees him as a better version of herself, minus the "weaknesses" that are (from an OOC standpoint) her redeeming qualities. Compassion, remorse, so on. With that said, his enemies fail to see his sharp wit, sly humour and pechant for mischief that I am lucky to be graced with.
In some ways, it's very odd for Narissa to interact with Alister, as it is, to some extent, for her with all the "new guard" (Salvador, Alister, Narl, Trakea, etc). I remember before the attacks from Springdale drove Alister to chase after combat ambitions, and he was focused almost entirely on stealth, trickery and robbery. Narl was as well, by the way. Both were adorably bumbling, too.
There was no visible snap, however, just a slow and gradual change as the attacks continued on him. I remember sitting in sewers, discussing combat with him - he had been almost desperate for me to review his logs and perhaps that discussion (I remember explaining herb balance and malloran stacking) was when I first noticed the change from the merry little sneak into a darker, more determined, fighter.
It was not until quite recently that I really realized how much growth he'd gone through - he kept wanting to spar me. The last we had sparred was his Blade entry requirements. His task was to stay alive against me and all I attacked with was a knife and jitsu. He failed, but it was not an easy win for me. A RL year later, though, we fought again - and I was the first to die. From the view of Narissa, it was one of those epiphanies: memory wound back to the day she had earned a kill against her own tutor, Demosthenes, and, finally, she understood the bittersweet mix of pride and sadness that moment had held for him. To no longer be the elder, but a peer, is a humbling experience, but one also laden with intense pride for helping bring the student to that point.
Many say Alister is wrong and cruel and terrible. Narissa, who grew up on the fringe of an older era, knows better. Alister is a throwback to the more brutal days before pacifism was rampant and duellism was even dreamed of. Alister has not ruined Avalon - he simply does not fit easily into the more coddled and quiet climate Avalon has become. I had hoped that he would help bring Avalon back to its more brutal roots (if you want safety and happiness, go play IRE with their PK laws), but the role of a pariah is not one I'd ask on anyone, so I understand when he vanishes.
I still will miss him.