One example could be the story of Shadrack Minkins, who was born in slavery in 1817 in Norfolk, Virginia. Minkins escaped to Boston in 1850 where he worked in a café. A few months later, the Fugitive Slave Act was enacted, and Minkins was brought in front of a judge. There, members from the Boston Vigilance Committee irrupted into court and led Minkins out.

A few days later, he arrived in Montreal, where he started a life in the restaurant business, becoming the owner of a place called Uncle Tom's Cabin on Notre-Dame street. After a while, he retired from the business and opened a barber shop. He had a wife and children, and died in 1875. He rests in (unsegregated) Mount Royal Cemetery.

The Old Montreal was the place where many Black people lived. During the French Colonial Regime, slave owners lived there. Many slaves (most of them Indigenous) worked as servants, but they were also working on the docks and in the restaurant business. When the English came, nothing changed much, but more African slaves were brought in. Since slavery was never regulated, the system kind of fell by itself before the official abolition, but the Blacks stayed in the business they were in.

For an African American immigrant like Minkins, the Old Montreal was the epicenter of the Black Community. Here, sailors from all around the world would be going to his restaurant. As time went by, many other Black immigrants came in and, by the End of his life, new factories would be built in the industrial zone near the Old Port.

With the traditional business of docking and serving, the train would also offer jobs to Black immigrants. The epicenter started to shift from the Old Port to the Southwest. It was actually considered American-ish and very chic to have Black busboys and waiters. On the Canadian Pacific, for example, all the busboys had to be Black. To this "casual' racism, you had to add greater restrictions to rent, as many landlords wouldn't rent to Black people. Some business owners wouldn't let Black people in, even if it wasn't technically legal to do so. It wasn't Paradise yet, but it was still way better than slavery.

To this, you would have to add the fact that Southerners enjoyed the fresh air of Canada during the Summer months. Many of them had country houses in the region in places like the Eastern Townships, and the CSA would even have a significant delegation in Montreal. I imagine some of those ex-Slaves must have ran into their old owners when they were on the train, for example. We have no record of this to my knowledge, though, but it is a great scene to imagine.

More on Minkins here : https://www.masshist.org/longroad/01slavery/minkins.htm