24 hours earlier:
After jumping out of the Shellraiser and running off into the darkness, Casey Jones found out that his powers of stubbornness did not leave him after all, and at the moment of crucial need, floppity-flop, he was on his feet no questions asked, no problem, sir. Well, a little bit of a problem, because, as Dr. Donatello commented later, he must have caused a certain amount of irreparable damage to his knees, 'running' around on his no-good ol' feet, since his injuries were not entirely healed yet. Plus, floundering about in filthy, freezing water with hockey-stick, used instead of a crutch, and with an enraged mutant at his side - not about to make for the best recovery, to say the least.
It would be pushing it, to say Casey's legs were back to normal. Nevertheless, at the very first sign of the mission going sideways, he didn't stop to think. His old instincts kicked right in, and Mr. Jones knew exactly what to do: get out of that idiotic wheelchair, and finally back on his two feet, bust some Foot soldiers' heads. Even though it hurt like a bitch, he had made his choice, however unwise and desperate it may have seemed. Even though, he did, in fact, keep losing his balance as an infant learning his first steps, experiencing crucial amounts of pain on top of everything else. But hey, at least he could walk! Not as much as run. But he could finally move his legs one in front of the other, periodically. And no lame leg-malfunction could ever stop him from getting to those loser Foot ninja motherfuckers and smear each and every one of their vile faces into the ground! For Mikey!
Michelangelo was the only one who got it. Having been not too long ago severely injured himself, he felt for Casey, and didn't walk on eggshells around his wheelchair. To exercise vigilante's injured legs, he carried his human friend in his very arms up to the rooftops every single night, motivating him to stand up and try to walk again. No doubt, the 'Arma Secreta' - a code-name the pizza-loving turtle goof gave their confidential night-time meetings, did their job. If only April found out... or Dr. D!? Their number would go up! It was all hush-hush, of course, and even Raph had no idea! (Haha, Raph! He'd probably break Casey's teeth for that.. well, the ones that were still there of course).
Not to beat around the bush, the poor handicapped vigilante didn't make it halfway to the docks, when suddenly Raphael dropped out of nowhere, snatching his buddy from the dark alleys right onto his shell-cycle.
Knowing that the first thing on his friend's mind would be to go get even with the Foot, Raphael made his calculations, estimating that Casey wouldn't wait, or strategize, or take into consideration his own health, before he'd leap right into the fire. That reckless lunatic! Raphael figured right away that Casey'd try for the docks, even if he'd have to crawl over there on all fours. And in all honesty, after all what happened, the turtle couldn't blame his friend for being enraged and reckless, because in this state of affairs they were two slices of the same pizza-pie.
"Raph, buddy!" - exclaimed Casey, grabbing his friend's shell and climbing into a sitting position at the back of his motorcycle, inwardly thanking every known deity up in the holy heavens for this blissful and unexpected surprise, "You didn't have ta' come pick me up... I was doin' jus' fine!"
"Uhm hmm, put that on!" - was the grumpy reaction, and a green hand pushed a worn out helmet into Casey's ribs.
"Ok, a'right, jeez, chill, will ya'.."
"Hold on tight!"
Casey didn't even have the opportunity to drop a word of non-compliance as they were literally flying through the air, wheels barely touching the road. The only thing left for him to do, was to grab hold of Raph's shell and press his helmeted head closer to the rough, yet familiar surface.
When, after a few minutes, they arrived at the docks, the Foot were already gone. But that was to be expected. The bad news was: Leonardo's unconscious body floating in the bay, in a quickly growing blot of blood rippling on the surface of the dark, nasty water. Together, they struggled for quite some time to pull Fearless out, and after a short CPR they took him to the lair, still unconscious, severely injured, but definitely alive.