The fourth doctor looked puzzled. "Paradox? What do you mean a paradox? Y-" His face slowly changed as the possibility hit him. He turned hack to the TARDIS, took out his key, put it in the door, and turned. It opened. "You! You're..."

He wastes no time, strolling right into the Tenth Doctor's TARDIS liked he owned it.

"Well, you've crossed into your own timestream. That was awfuly irresponsible of you! It goes against everything we learned at the academy! Everything the High Council stands for!"

He stops, turns to ten and pulls a toothy grin.

"I think we are going to get along fine. Still, I don't particularly care for what you've done with the old girl." He motions to the TARDIS interior. "It's very dark, and these coral structures really aren't my cup of tea. Now then...Let's find out what 'pulled' you in the other direction."