Kay, Miles and Gumshoe's relationship would be...
The perfect investigation team
Friends, thick as thieves
A romantic threesome
Other (you might want to explain)
It would be awesome if you guys could also comment and explain your answers (especially if you see their relationship in more than one way). =3
As for me...it would be like friends bordering on family. I love how Miles may seem distant at first, dealing with Kay on strict serious-business terms, but you can see that he genuinely cares for her (especially when he chides her, or when she tells him that he has no sense of fun). Add Gumshoe, who looks up to Miles and looks out for Kay, and it's like she has a dad and an uncle...and at the same time, two close friends.
...I'd make this more tl;dr but I have FINALS XD And, I kept the spoilers to a minimum. If you're going to make spoilery comments, please put warnings. ^^ Just in case.
YAY LET'S HAVE A DISCUSSION LAWL