Things are heating up again between Chris Brown and Rihanna. Chris reportedly attended Rihanna's 24th birthday party over the weekend, although if it was up to him, you'd never know that he did.

TMZ reports that Chris tried to keep his attendance under wraps by forcing people at the party to sign confidentiality agreements, and refused to enter until everyone had done so. Not everyone signed, but eventually he made his way in the door.

The pair reportedly sat with each other and held hands.

"RiRi made sure Chris was having a good time," said a source. "But then he kept a low profile, spending most of the night in a corner with a few pals."

[Digital Spy]