"Shouldn't you be in bed?" he shot back in a sing-song voice, looking around the room. Bella was old enough to try and tell him what to do, and for it to carry some weight. That didn't mean Sirius had to listen though, and with neither his parents or hers present, he could pretty much say what he liked.
He wandered into the room, looking from side to side at the various things she had set up. He had no idea what they were for, but a vague notion of what they might be about. Sirius gripped onto a table and used it to swing towards a gently simmering pot, "What's this?" he asked, already moving on to the next nearest thing. All sorts of vivid colours spat inside their tubes.
"Is this where you were all night? Mother thinks you have a job. Is this your job?" He swung back around to look at her, interested in what she was writing. If Bellatrix was doing some sort of important experiment, he could help. He didn't know all that much about potions, but he'd watched his father brew quite a lot. Maybe when he came back for Christmas he could help her then - he'd have had some Potions lessons by that point, and could be very useful.