So do we know why the Master/O put so much effort into flirting with Yaz throughout Spyfall part 1? Because I've got four different options and theyre all as hilarious as each other.
He picked up on something going on between the dr and yaz, so thought that he could make the dr jealous. The doctor seemed to either be completely oblivious, completely fine with the flirting, or not bothered in the slightest.
He planned on trying to steal Yaz as his own companion once he revealed his identity (see: 'stick with me, yaz, because i control everything'). She rejected him once (not even outright! She just didn't reply!), and he gave tf up. All that buildup and he's like yeah nah not worth it.
He actually did fancy her.
Waiting for the Doctor to work his plan out was getting boring, so he essentially added a romance plot into his spy drama to spice things up a bit.
Really not sure which is my favourite.