After you took Cait's contract from Tommy you would send Dogmeat back to Sanctuary and wonder with Cait to an abandoned store where she speaks in her strong Irish accent clearly seems to be on chems

"Why the fuck are we here at an abandoned store? we should be out killin big 'scary' angry dumbasses."

She would turn around and you could hear her take some jet which immediately upset you due to how strong and addicting chems are and hearing someone like Cait take them just made you even more sad