Episode 1.4, Some Welcome Home Party (Where Claire Did Too Many Voices)
Honestly, it's a shock that Kat hasn't just thrown up her hands and walked away yet because Claire's voice-acting ability is straight up atrocious. #SorryNotSorry
In this episode, the recently un-deceased Sirius is revealed to the Order and Kat is convinced people aren't happy about it. Kat is forced to put up with Claire's rendition of God Rest Ye Merry Hippogriffs, Mad-Eye sounding like a pirate, and then Harry returns and Kat's dry sense of humor almost breaks Claire. A harsh payback, to say the least.