If there were borrowers in the house where Brad was raised, it must have been quite a sight to see giant scary humans carefully, gently and diligently caring for a tiny baby.
omg I loved this scenario, I've never thought about this possibility before
Canonically, FOR NOW, there weren't any borrowers living in Alex's parents house, but let's give this a headcanon try because it deserves it!
It wasn't only quite a sight, but also a VERY scary and unsettling sight. The borrowers were TERRIFIED to see gigantic humans taking care of a tiny lil baby "imp" and they were, on top of it all, afraid for the kid. He seemed to be save for now but for them it was a matter of time until one of those humans slip their hand a little and doom an inocent baby. For what they best know, they could be raising him to be a pet!
The borrower girl wanted to save Brad and take him with them to raise him properly, but her brother wasn't excited to risk their lives trying to "kidnap" him.
After some arguing and observation, they decided to get into Brad's cradle at night and "rescue" him. They weren't worried making him cry bc the humans in the house would hardly listen to a tiny baby crying from other rooms in the house.
But let's say technology saved our baby Brad...
How else do you think Alex would act when hearing the soft cry of his baby boy through the baby monitor?
Alex was PISSED at at first seconds, just like a mother duck wanting to keep her babies safe, but he soon calmed himself down to best deal with the situation.
The borrowers freaked out, the girl went for being paralyzed in her place in fear while her brother yelled at her to leave the baby there and FUCKING RUN THERE IS A GIANT HUMAN STARING AT US.
For his turn, Alex didn't say or do anything. After spending so much time with other imps and dating a borrower itself, he quickly understand what was going on. These imps probably saw him with Brad through the walls and thought he was in danger, it was just a misunderstanding.
But Alex also wasn't in the mood for talking and explaining, not only because he was tired of dealing with fear, but also because he knew they wouldn't listening, it wasn't worth the stress. So he simply standed there and waited for them to leave, knowing his presence alone was enough warning. He'd take further action if they tried to run away with his son (which he thanked to the heavens it wasn't necessary).
The girl eventually snapped, left Brad in the cradle and started to run to hide from the toweting human above them, following her brother. She couldn't help and be surprised though, the baby seemed so happy when he saw the human and was waving his arms at him, as if he wanted to be held by that giant figure, way bigger to him than to them.
They had to leave the house because they were seen, but I bet the incident never left their minds.
Maybe humans and imps could have family bonds afterall!