Hi, lighty110, welcome to PsychCentral (PC).

Is James your age or older than you (are you Sarah's age)?

The only behavior you can control is your own and trying to hold a boy down in his own room to paint his nails is definitely flirting behavior? Put yourself in his shoes; here he has a couple girls in his room trying to hold him down (on his bed?) trying to do things to him Sounds pretty "hot" to me for a teenage boy. It could be he messaged Samantha to make sure he "got in trouble" so he would not be too tempted and would have additional "control" over having two girls crawling all over him. Samatha is safe because she is his girlfriend so behavior like you two were doing would be okay with her but I think you should tone yourself down some when you are around him, see if he does not make as many comments as a "relief" valve?