"Doctor, you've got to save him! This one is different."
The Doctor already knew that.
He'd seen the way Captain Jack looked at Rose and how she responded, but he'd also seen Jack looking at him. Centuries of keeping his companions at bay both physically and emotionally were at peril. He'd already felt himself drawn to Rose, and resisted for both their sakes. Bringing Jack on board would change everything. No one could hold out against that smile for long.
Time was running out, but the decision had been made before Rose even asked.
The Doctor wanted to dance again.