So, because apparently I'm more curious than spoiler-phobic, I read your original comment, which made me go back and re-watch Adore, which is one of my favouritest [totally a word!] TW vids, and thought I'd point you towards it in case you've never seen it. It's all about abandonment - how Jack was abandoned by the Doctor, and then in turn abandons his team, and it's all tied up with/refracted through Capt John and his issues... Awesome, awesome vid, and apparently very apropos. *loves circular themes*
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