Altered Au: Boris and Mike are twins but since the wheelers couldnt afford 2 more kid they sent Boris to live with Karen's( Mrs Wheelers ) sister which was Boris's "mother". His "father" went to jail for child abuse, he got reunited with his family(The wheelers) . Theo did run away after Boris left and they ran into each other during a family vacation of the wheelers. Season 4 hasn't happened yet and yes they had a dramatic good bye when Boris left aka the taxi kiss scene but it was Boris boarding the taxi.
Credits:
First tiktok
https://vt.tiktok.com/ZSeKMUct3/
Second TikTok
https://vt.tiktok.com/ZSeKMRh29/
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https://vt.tiktok.com/ZSeKMjMGN/
Forth TikTok
https://vt.tiktok.com/ZSeKMFs4H/
Fifth TikTok
https://vt.tiktok.com/ZSeK6KLot/
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https://vt.tiktok.com/ZSeKMhryH/
Seventh TikTok
https://vt.tiktok.com/ZSeK6ouRf/
Eighth TikTok
https://vt.tiktok.com/ZSeKMVStL/