I practiced last week for the first time with a band, we mostly played originals and a few covers. Basically the singer plays rhythm so as I play rhythm too I obviously have to rethink and start playing lead and stuff.

Most of the stuff we played (very good) is in D and revolves around D, C, G with the odd F, B and Bb in there. Now I have a good feel for music and I've managed to put together some lead stuff for 3 of the songs (I've only had a week).

However I'm not gonna play leads all the time and I want to add some colour and contrast to the rhythm sections but how do I do that? The rhythm player pretty much only plays barre or power chords so I've realised I can hit more trebble strings to add a different dimension but what else could I do? We have different guitar sounds which work well together so I don't want to drastically change my sound.

It was always gonna be a massive learning curve for me playing rhythm but with the lead aspect as well it's looking like it's gonna be tough so any "leg up" would be tops!

For playingin the key your in which is d, learn the d major scale or bminor pentatonic which has the same notes, also learn places where chords are played higher up the fretboard, and add in extra notes. When playing chords get all your fingers independent and try adding in different notes when playing chords. Hope this helps.
you can try just playing arpeggios of each chord behind his rhythm....

or possibly playing an inversion of the chord in a different position.

also if he plays like a Cmajor you can play an Eminor or E5 and change the implied chord to Cmaj7... and do things like that, just don't over do it....

hope that helped
Quote by Dirk Gently
Some pieces are only meant to be played by people with six fingers on their fretting hand. Sorry.
You could try different voicings of the same chords, or try playing chords\dyads that add extensions to the chord the other guitarist is playing. E.g. If there's a D chord being played you could play C# and E together to extend the overall chord to a D9.

(I hope I've got that right!)

There's lots of options really. I'd get experimenting!