Yes, "avec merci" is French--it means "with mercy."
I got into Hands Off because of this review (
http://www.sleepisfortheweak.org/reviews/sonote/), which is written by the woman who's doing the script adaptation for the Tokyopop edition. She swears up and down that it isn't shounen-ai, and she's read the whole thing in the original Japanese. So I tend to believe her.
It's true that Hands Off is a title that would probably appeal to shounen-ai fans because it has pretty boys, angst, and deep emotional connections. You could see the relationship between Kotarou and Tatsuki as homosexual IF you wanted to, but there isn't a bit of explicit evidence in the volumes published so far--in fact, I think there's evidence to the contrary.
(Quick summary of the set-up: Kotarou Oohira causes psychic reactions in the people he touches; when he was a little kid, he gave his cousin/best friend Tatsuki the ability to see the past. Tatsuki saw lots of scary things, drew away from Kotarou, and became the dark/silent/angsty/screwed-up type. Years later, when Kotarou is 15, he is reunited with Tatsuki when he moves to Tokyo and has to share a house with him. Then Kotarou makes friends with Yuuto, a classmate who can see emotional auras. Together, they fight crime! Well, mostly Kotarou gets kidnapped and the others have to use their powers to save him. Oh, and as of Volume #3, Kotarou still has no idea that anyone has any powers at all.)
Both Kotarou and Tatsuki spends pages and pages wishing that they were close again. But they always express this wish in terms of wanting to go *back* to the friendship they had as little children, something that was obviously non-sexual. Kotarou even describes his early friendship with Tatsuki as being like he had "a brother." And in the climax of one story, as Tatsuki is saving Kotarou from death, they share a moment of psychic communication in which they're both drawn as little children. So I think that their relationship is meant to be familial and non-sexual.
Plus, Kotarou is obviously interested in girls from the very beginning, and gets a girlfriend pretty early on. And in Volume 2 (slight spoilers),
[spoiler]After Tatsuki stops Chiba's machinations, and Kotarou and Mio are reconciled, Yuuto looks at his aura and thinks, "What a nice color that is on you. Cut it out before you make me cry." The implication is that Tatsuki, despite his gloomy exterior, is having happy fuzzy feelings over Kotarou and Mio are reunited. If Tatsuki were secretly pining for Kotarou himself, he would have been at least somewhat unhappy, and Yuuto would have seen it.[/spoiler]
So I think that their relationship, while really intense, is meant to be familial and non-sexual. Honestly, that's the whole reason that I started reading Hands Off, and why I keep reading it despite its flaws (it does have some)--it is SO RARE that authors acknowledge how intense and life-changing non-romantic relationships can be, so I'm always really happy when I find one that does.