Union is the unofficial Roleplay server, and has a much larger RP community. I'm sure there are RP'ers on defiant, but you'll probably have to track down an RP supergroup since I don't think they have any regular social meets like the union GG meet, which does help for attracting RP'ers together.
Try putting a comment like "Roleplayer looking for roleplayers" in your search comment and broadcasting occasionally asking if there are any RP'ers in the zone.
Hi, I have a number of chars on Defiant (yeah I chose it as my primary server for the name too ) and I try to get as much rp in as possible.
Though I'm fairly flexible with my team ups and dont mind teaming with non rpers ( I just ignore any OOC stuff they mention).
So if you see any on of my heroes around give a shout (most my chars dont mind exemping down either).
Spurr (sonic blaster)
H-Bomb (empath/rad defender)
Vaacume (grav/kin controler) (rp only char..hates humans)
Green Hydra (spine scrapper)
Albion Flame( I/F Tanker) (rp only char,not the sharpest tool in the box).
I've rerolled my defiant main (Tower of Power lvl34 tanker) on Union, now he's lvl 20, and an alt... In favour of my new main
@ShadowGhost & @Ghostie
The Grav Mistress, Mistress of Gravity
If you have nothing useful to say, you have two choices: Say something useless or stay quiet.
well as a big old time defianteer, i have started going to the GG meeting with my PB who exists on both severs, it's fine, i have to say i am sad enought to lvl them both up on both severs, jsut not very much, certainly thouhg the Union Rp commiunity is much more (so far as i can tell) accessible, main becuse thay don't hve to run for the hills went hordes of ravening power games attempt to hunt them down 
though i have seen a post in the defiant bord of peeps trying to start a RP SG
I am a new player to CoH/CoV. So, not knowing where the roleplay is on, I just picked the server with more appealing name. I got on Defiant.
Is there any roleplaying meetings / anything going on in there? Or how could I find some roleplayers? Now that I have played there for a month, I wouldn't like to take a leap to Union.