This song basically takes place in yet another short lived timeline, where after Pico gets corrupted, instead of BF going to the place where Corrupted MM would soon be, BF and GF go striaght to DD, as he could fight off the corruption while they would basically be of help. Even though BF has no visible demon powers, unlike GF and DD, BF’s velvety pipes work on the corruption, and because of plot armor, BF would not get corrupted if there was a fight with Pico, Skid, Pump, and MM, but scenario would be ALOT like Full Circle, so am I going to a make song about that battle? The answer is no! The lore tells you about as much.
This is the vocals version of the song you just heard, if you want to hear the instrumental only, click this link to listen:
Source
Good.
What if GF brought BF with her?