Singlor is one of the two travelers that the player will encounter throughout the game. They are found in various locations. Most of them are well hidden however.
There are 16 encounters, shared between Singlor and Nala - Singlor is encountered once in every town and rift plane, as well as the City on the Edge for a total of 8 times.
The order of the conversation does not matter wherever you find them.
Singlor was a man who experimented on gravity and space time, in the hopes of saving the world from the threat of the black hole that was later shown to be created by The Darkness. His experiments proved disastrous when his wife Nala dabbled with his work and caused an accident that shot them into different space time. This is why they have trouble finding each other during the game. Singlor has been trying to figure out the problem since the accident.
In the Ark of Time DLC, You can see Singlor and Nala together in the background of the final chapter.
He seems to be wearing a blue coat with black trousers. He is mostly seen holding his chin in concentration. He is the stressed one of the couple where Nala is sad and gloomy.