Professor Martin Stein was no stranger to observation. It was a large part of his education and profession. So, when he began to notice subtle changes to Mr. Snart and Miss Lance, he decided to investigate further.
During one battle, he noticed just how in sync they were as they fought. Very often, it was like the rest of the team wasn't there and they were only fighting together.
A few days later, as they discussed their next move against Savage, the pair wore identical expressions in their eyes and even turned towards each other at the same time on several instances.
While observing another battle, he realized just how similar their fighting stances had become and how, once again, they fought so well in relation with each other. At one point, Miss Lance's staff had been knocked away from her. Mr. Snart tossed her the Cold Gun and she used it as if she had been since the beginning. Likewise, Mr. Snart picked up the staff and began wielding it commendably as well. He knew they trained well, and often trained together, but perhaps he didn't know the extent of it until now.
"Gray! Could you focus on the fight, please, instead of whatever Sara and Snart are doing?" Jax chastised through their link.
"Of course, Jefferson. My apologies," Stein replied. But he knew he'd be monitoring them more closely.
Over the next few weeks, it became more and more clear to him. There were lingering glances that he was sure they thought no one noticed. Perhaps a few touches that were meant to look like accidents or happenstance. Stein had found out as well that it was Mr. Snart that convinced Miss Lance to not kill him in Russia and had given her a passionate speech about not being a killer anymore. It appeared that Captain Cold had actually warmed the humanity in the White Canary's heart again.
Once they got Mr. Snart back after the ordeal at the Oculus, Martin was certain he knew what he was seeing. It didn't take a genius to notice their actions now (though, in this particular group, it did seem to take a genius, seeing as how no one else saw their burgeoning romance). He even saw Mr. Snart sneak into Miss Lance's room a few times. Apparently new love makes one sloppy, even when being stealthy was essential to one's former occupation.
He couldn't help but grin to himself the day he caught them passionately kissing in the study. They thought they had gotten away with it, but between the sounds Stein heard, and Mr. Snart's upside down book, it was more than obvious what he had accidentally interrupted.
On the day they finally admitted to their love to the crew, Stein refrained from the smug look he wanted to give, instead only mentioning that he had suspicions. (It was enough to hear everyone else's surprise to make him feel pleased with himself for figuring it out long before the rest of the Waverider crew.)
And now, as he performs their wedding for them (maybe going to rabbinical school wasn't such a waste after all), he's delighted to see two completely different people than those he once met. And as he finally declares them husband and wife, he can't help but think to himself, "Astonishing!"
