Sirius once read a story by a stuffy old man with a handlebar moustache about a barbaric queen's lover. They punished him by pitting him in a pit and seeing whether he chose the door with the beautiful lady behind it, or the one with the ravenous tiger. The queen and king thought it all in good fun, but the whole while there's this internal debate on everyone's mind:

The lady, or the tiger?

It was an incredibly boring story, with too many superfluous words for Sirius' taste, and he was forced to read it by his stupid, bald, squat, sweaty tutor whom he despised for using too many unnecessary words to make Sirius' stupid, evil mother think he was brilliant (it worked), but now, as he stood watching his mother flame his face off of the tapestry, he had a choice:

Well, Sirius, here it is: the lady? the tiger?

In his case, he would meet the tiger, no matter how far away he ran with the lady. His family would always catch up.

So he ran, as quickly as he could, towards the door. He could hear his mother behind him, still mid-rant. He knew he should possibly knock Regulus over the head for good luck, or murder Kreacher for the betterment of all humankind, or something, but thought that might be pushing it, so, instead, he saluted his father, brother, and the papery, old house-elf, and curtseyed to his mother before she pushed him out on to the pavement with a roar.

Things tended towards the slow-motion after that. He lay on the pavement for a little while, letting the spring rain wash over his face and make the blood run from his elbows and cheek onto the cement, growing dizzier as moments passed. It may have been and hour or a minute before he gathered himself enough to apparate to the Potter's. Why the Potter's? Why not the Lupin's or the Pettigrew's? He tried to justify it later, but, really, it was just the first place the thought of.

He tried to convince himself he was not unhappy to have left, not unhappy to have not said goodbye to Andy, not sad at all. He told himself, as he tripped numerous apparition and security wards (Charlus was an Auror, after all) that he was just overwhelmed, that running was hard, but he couldn't help but regret.

No, he did not miss his conniving, blood-obsessed parents, especially not when Dorea came out, took one look at his cuts, and enveloped him in a hug. He didn't miss his spoilt, Death-Eater brother, especially when James let him just sit and stare at the roof for three straight hours, and not interrupting.

He didn't know what he missed, or what he didn't do, and he never really placed a finger on it, but it was always there, a niggling longing.

But, from then on, Sirius Black lived as much as he could.