Neither of them trusted each other - and for good reason on both sides. After all, they were on opposite sides of what had been a war, her side tenuously holding on and fighting, often off the radar of most witches and wizards in the country. But not to Barty. No he worked at least five days a week to track them down. And they tried to bring down his world.
But they were both quite human, was the thing. Andromeda had people she cared about, and Barty had chosen to prioritize Vera Lestrange over the others. Plus, the people he was doing so for cared about the girl's safety. Thus, Barty worked for it. Of course, he was more than willing to use what means were necessary to take her in, something potentially arguable with those who cared about her.
"We have business to discuss," he replied frankly, being honest as there was no reason to hide his motives with tat. He was not invested in her life in a way that left him weak, but he wasn't quite so much to make him cruel.