Disclaimer: I do not own Tomb Raider Legend or anything else that anybody in the known universe could sue me for. I own nothing.
Agony
It started out as a casual thing. She hadn't known him as long as she had Zip, so there was no worry of ruining any sort of friendship. At first that revelation hurt, but after a while it stopped mattering to him. He looked foreword wholeheartedly to their meetings about once a month. She made him happy. He made her happy. Mutual happiness. There didn't have to be love beyond that of inevitable friendship. For a while they were perfectly happy with the arrangement.
That was until Lara was on one of her exploits. When she dove off a cliff towards a vine that would most likely snap and plummet with her. Alister realized what used to be simple fear for her safety was now coupled with a deep-seated agony at the thought of her loss.