After everything that happened
around Valentine's Day, Sideways had resolved that he just couldn't stay at the Autobot's base any longer. He'd only waited this long to give his legs a little more time, but once he'd heard the zombies - and oh, he recognized those growls and screams from so many films - he'd decided it was time. He wasn't going to do anyone any good sitting around here. He was just endangering them anyway, now that Alice knew where he was.
He'd kept himself to himself for nearly six months, and he left only two signs of his passing: two planks, with messages carved into them with his stubby claws. 'Aim for the head', and 'Don't let the humans get bitten'.
He'd escaped out into the city, finally, though he wasn't folded down into vehicle mode. He wasn't certain if he was ready for that, yet. Besides, there were zombies to shoot, and he has better aim in his base mode. So, Infinity, have yourself a miniature giant space hamster robot, with a saw and a sniper rifle out. He's here to save your hoomans!