My reply to this post
Erza was serious in her fight against Jellal. Just because she didn't run him through doesn't mean that she wasn't serious about trying to take him down. Erza was too self-depreciating back then - too willing to take the bullet when it concerned her past because of her guilt.
And Erza has gotten her face shoved with her past on many occasions - the entire deal with Jellal on the run and with Milianna and Kagura gunning for him is bringing up the loose ends of what Jellal did.
Erza took it upon herself to be Natsu's big sister/mentor. It's why she lets him take as many risks as he does. She wants him to grow stronger than even she is. Natsu gets beat as often as he does because his power fluctuates depending on how angry he gets and if it's a 'do-or-die' moment. He is also still learning about how to manipulate his power. Erza has pretty much maxed out on what she has to learn so far and is just in level grinding mode.
Facing someone of Bluenote/Gildartz's level is suicidal and Erza would never tackle someone like that without being part of a team situation. She's too smart for something like that. Asuma was enough of a fight on his own for her.
She's an author favorite and a fan favorite and she has MC Determinator lvls so there's pretty much no way that she's gonna lose to most of her fights until she fights someone meant for Natsu to take down, like Jellal was.