I was looking at it from's Faith's POV and from the "father figure" side before. I definitely don't think he's a father figure to her or that Faith would have a problem reacting to the hotness that is Giles.
That said, you guys do have a point about Giles: what would he get out of the relationship? His most successful Buffyverse relationship was with Jenny, so let's look to see what he got out of that. She was younger than he was, but probably not by more than a decade. Certainly there was nothing pervy about the age difference. She was also "edgier" in terms of technology and whatnot. She could accept his past because she had one of her own. When push came to shove, she learned enough to try to do the right thing. She cared about her students -- even and perhaps especially Buffy. She accepted consequences for her actions and tried to fix wrongs that she had created. Jenny was an intelligent, kind person who made some mistakes, but she knew how to deal with those mistakes and she genuinely tried to fix them. She and Rupert could bond on an emotional level. Her edginess and youthfulness challenged him to broaden his horizons and to do things he wouldn't normally do. Most important of all, I think, she made him smile.
Also, there was hope for a future with Jenny. That was what was so tragic about her death. With her background and leanings, Jenny could have been right in the thick of things with Rupert and possibly even joined him as part of the Watcher's Council. She wouldn't have been scared off like Olivia was or kept at arms' length by her relationship to one of the students, like Joyce was. With Jenny, Giles could have had a partner in every sense of the word. He could even have married her and had kids with her, if he had wanted to do so and their relationship had progressed accordingly, without having that desire have to conflict with his work or his other important relationships (like those with the Scoobies). That was what was so tragic about Jenny's death. They were just embarking on that adventure with one another when Angelus ripped Jenny away from everyone. She could have been a huge asset to the group. Above all, though, she could have been a true partner for Giles.
Some of this, I can see Faith providing. She could deal with Giles' work and life as a partner because she is in the thick of things, too. She could bond with him over having once been on the wrong side of the good vs. evil thing. She could challenge him to get out into the world more often or to try new things. Like dancing. I can totally see Faith dragging Giles out onto a dancefloor. Hilarity would ensue. Also, Faith does seem to genuinely care about her work and about righting past wrongs... especially now that Giles offered her a ticket out of the slaying life and she chose to remain in order to try to do some good. In many ways, their personalities and temperaments would be well-matched.
But there is no future with Faith. She's a slayer, not a Gypsy Witch/teacher. She has a short shelf-life and most of that has already been used up. Even given their significant age difference, the chances are pretty great that Giles will last a lot longer than she will. Furthermore, she could never be a partner to Giles without interfering with his other important relationships. The Scoobies would have a very difficult time accepting her. Faith would always be jealous of Buffy's place in Giles' heart. I think Buffy would be jealous, too. Surely Giles would not wish to expose either of them to that sort of tension or competition -- especially when he finally gets about the business of getting back on speaking terms with the Buffster. There is already enough tension there to fill the Grand Canyon. To be honest, I think the rest of the Scoobies would feel sort of betrayed if Giles were to take up with Faith. I mean, she did try to kill most of them at one point or another. They are only just starting to come to terms with her changed ways; I think it would take a long time for them to trust that Faith's intentions toward Giles were sincere. Bascially, from Giles' POV, the Faith relationship would open up a lot of different cans of worms. I'm not sure he would want to do that.
So yeah. I think it would be unrealistic of them to not at least notice each other as attractive, single people. I think Faith, especailly, would have to be crazy not to notice the appeal that's there. But I'm not sure Faith can provide for Giles not only what he deserves, but what his prior relationships seem to indicate he is pretty picky about seeking. Giles seems to be waiting for just the right person. He's slow to warm up to the idea of romance and he certainly puts it on the backburner in favor of his work. He seems to want someone who can be a best friend and a partner as well as a lover and he is very slow to take steps in that direction. Faith has always seemed to want one no-strings-attached fling after another and does not seem, ideally suited for the long-term partner role, so I don't think Giles would see her as a viable candidate.
Darn it! We need a viable candidate. Joss needs to write in another Jenny!
