Theseus is usually imagined as everything Newt is not - the hero archetype, basically. That's what everyone at MACUSA is expecting when the older Scamander drops by to check in with his brother.
...they get an auburn-haired man with a dreamy expression and trouble making eye contact. Theseus is VERY MUCH Newt's twin brother, except he's exactly as much a huge enthusiast of Defense Against the Dark Arts as Newt is for Care of Magical Creatures.
+ For Theseus enthusiastically discussing Particularly Nasty Dark curses and the defenses thereof as everyone around him goes pale.
MINIFILL Prepare for Trouble
...they get an auburn-haired man with a dreamy expression and trouble making eye contact. Theseus is VERY MUCH Newt's twin brother, except he's exactly as much a huge enthusiast of Defense Against the Dark Arts as Newt is for Care of Magical Creatures.
+ For Theseus enthusiastically discussing Particularly Nasty Dark curses and the defenses thereof as everyone around him goes pale.
AO3 link: http://archiveofourown.org/works/9610565
Meme link: http://fantasticbeasts-kinkmeme.dreamwidth.org/1184.html?thread=1992864#cmt1992864