As appreciative she was of Ignatius' ability to not move too much, figuring that was the sort of skill honed by most book-obsessed Ravenclaws that could waste entire days reading in the same corner of the common room without any sign of outside awareness, she also liked that he remained quiet through the process. Not that she wouldn't like conversing with Ignatius under other circumstances as she rarely found him disagreeable despite their differences, but her attention span could be somewhat fragile and the less distractions the better.
It took awhile, not that Mabel was keeping track of time, but she finished painting Ignatius's figure before working to fill in the surrounding details and the dark background. She found him attractive enough without actually being attracted to him, but she was now quite aware of every muscled limb of his body. Perhaps it had been an overly intimate favour to ask, realizing she wouldn't have done the same in his position. Maybe she owed him something in return, but unless he asked she had nothing to really offer.
Technically she didn't need him there to complete the painting, but she kept this fact quiet instead of inviting him to leave, not examining her reasons why she wanted his company.
"You're cold," she finally broke the silence, setting her paintbrush aside. With oils taking so long to dry, she'd need at least the next day to wait before doing highlights and some minor adjustments. There were charms she learned for drying the painting faster, but she always preferred how it looked when left naturally.