In D.Gray-Man, the relationship between Allen and Tyki is laden with Ho Yay and Foe Yay subtext. Some notable scenes include Tyki "killing" Allen (which resembled a sort of "violation," with Tyki sticking his hand into Allen), the suggestive dialogue with Tyki telling Allen, "Don't be so cold, boy. An Exorcist made a Noah strip down to his underwear. Was that the first time you did it? Do you think it was destiny for it to be us?" and Tyki seeming miffed when Allen tells him that he'd done it to many people before. During their fight later, there's another Does This Remind You of Anything? moment with Tyki telling Allen, "This is giving me the thrills. I'll break you, one more time, with this hand!" Not to mention Road telling Lavi that Tyki likes Allen as she does (this being after it was established that she likes Allen enough to kiss him).
Not to mention the fact that Tyki destroyed Allen's Innocence.
And there's Allen's constant bickering with Kanda, who seems to be the only person who manages to piss him off to the point where Allen breaks his All-Loving Hero persona and makes vindictive jabs at him. Also isn't helped with the fact that all their petty arguments are like those of a bickering couple's...
Or how about the little piggyback Link gives Allen while Allen was wounded and alone, away from everyone else? And in latest chapters it's really noticeable, especially in chapter 211 with Allen freaking out over learning that Link died.
Chapter 212: Link shows up outside of the inn Allen, Kanda, and Johnny are staying at, with Kanda calling him a "stalker"..
Also, Cyril clearly likes the ladies but he is also obsessed with Tyki and even flirts with him a couple of times. And then there's that one scene where he says that Tyki's beauty arouses him, with Tyki replying "You're giving me goosebumps."