Why Did Gregory Kill Cassie in FNAF: Security Breach — Ruin?

In one of the endings for 'FNAF: Security Breach — Ruin,' players watch as Gregory betrays and supposedly kills Cassie during her escape. But why did he do it?

Who is Cassie in FNAF: Security Breach Ruin DLC? - Gamer Journalist

Stream Cassie Sings A Song For Gregory (Five Nights At Freddy's

FNAF SB Ruin - All Endings Explained; Scooper Ending and More

DLC Cassie is now confrimed as Gregory's friend :D by NoriNori77

Cassie, Five Nights at Freddy's Wiki

🦃 Yeti for Action🦃 on Game Jolt: New Security Breach game

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Y'all I think Gregory's gonna be the Elizabeth Afton of this new

Any theories on who Cassie is and why she's helping Gregory? : r

Security Breach Ruin Dlc Cassie and Gregory by Abel186 on DeviantArt