The Origin system(Warframe) gets dropped into Borderlands circa the ending of 3.

[Agent23]

ROB decides that both universes lack sufficient gun bling and weirdo status effects so he just grabs the Origin System from Warframe and plops it somewhere close to Pandora in the Borderlands universe.

For further keks the ROB equips every single faction's ships with BL FTL and gives them star charts of the surrounding universe.

Fight!

 

[Scooby Doo]

In other news, Vault Hunter applications skyrocketed over 100,000% over the course of a single Terran night.

 

[Agent23]

In other news, Vault Hunter applications skyrocketed over 100,000% over the course of a single Terran night.

Vaults in both games function a bit differently.