Ok, in all seriousness (or, as serious as I get, anyways), I do actually have a reason for thinking these two cuties would make a great couple.
Think about it, they totally balance each other out. Tasuki is fiery and hot-headed; young and inexperienced in life and the workings of the world (for the most part anyways, though, he has been through quite a lot for someone his age). Chichiri is calm and cool; older and capable of leading his companion with an experienced hand.
Tasuki is always represented by fire; Chichiri has a history with water.
Tasuki is strong, a great fighter; Chichiri, though capable of fighting, is more of a pacifist.
Aside from the fact that they're in a perfect balance, they also have shared quite an adventure together. Who else would understand what a Seishi has been through besides another Seishi? And since all the others are DEAD, that leaves only these two to be there for each other when the memories threaten to take over and the feeling of isolation starts to arise.
And, gosh darn it, they're just so damn cute! ^_^
Besides...Tasuki hates women. =P ::laughs:: Actually, Yu Watase said in an interview somewhere that if any of the seishi were to be gay it would be Tasuki.