Orvin's family

So Orvin's wife was kind of successful in her own right, more so than Orvin, and when she met Orvin, she was insistent that she doesn't want to have children. So when Kenny was brought to them, She understood the situation but in the future, ends up resenting Kenny because she has to sacrifice her career for a kid she never wants.

Kenny's introduction also meant the end of Orvin's happy marriage life, and in a way got closer to Kenny, because of Kenny's loss, his loss as well, seeing his sister in Kenny, his wife estrangement and also wants to make up for the bad actions from his wife.

Furthermore, as Kenny becomes an adult, he gets better at the glassmaking which makes Orvin a bit jealous, even resentful, reminds Orvin of Kenny's dad who was also a protegee and a rival that married his sister, they never got along, and any time Orvin sees that side in Kenny, he hates it.