Regina was still avoiding the whole town like the plague, especially Emma, since she was the one who brought Marian back with them in the first place. She was poofed away from the scene, Robin's camp was attacked by a giant ice monster. They were all knocked out on the floor (probably due to Ms Swan's lack of magic training), except one, Marian.
She wasn't entirely sure why, but she saved Marian and the rest of the camp that thought that they could fight magic with twigs. She smirked at Marian being knocked over when she tried to fire an arrow at the monster. Her smirk only grew when Marian, the woman who called her a monster, practically begged for her help. She disappeared in a puff of purple smoke, a look of disappointment and regret crossed the face of the forest smelling woman that stole Robin away from her. In that same moment Regina made a choice to save them all, the only witness to her good deed was the woman that hated her the most.
She appeared behind the monster and in seconds managed to break up the particles of ice holding the creature together. A gob-smacked Marian and the unconscious merry men (and the 'saviour') were all that was left in front of her in the forest. She had to strain her ears but she heard it Marian actually said "Thank you."
The rest of the camp soon came around to see that the monster had been taken care of by the Mayor herself and was still standing in front of them awkwardly.
Robin stood up and went to his wife. "Regina?" He seemed confused and disorientated, but he, along with the rest in the camp were alright.
Marian broke the awkward silence and surprisingly turned to the former Evil Queen. "Maybe you're not a monster."
Regina nodded in thanks and responded. "Maybe I'm not."
At this time Hook was helping Emma up, as Regina turned to leave.
"Regina we've been looking everywhere for you, we need to..." Emma's words trailed off as the queen disappeared in her usual cloud of purple smoke. "Talk abut this." She finished, staring at the already fading smoke in front of her. Hook just patted her on the shoulder.
Later that same day, Emma followed Regina into her vault to apologise once again. Regina had her arms folded and was standing facing her mirror. She looked up when she heard footsteps.
"What do I have to do to get you to leave me alone, Miss Swan? Go away."
At that exact moment, just before Emma got the chance to retaliate, there was a blast which knew caked both of the sorcerers off their feet. They both looked at each other and the shock on their faces answered the question. It was neither of their doing. They both scampered to the feet towards the door, the only exit in the vault, and tried to open the door. It was blocked, Emma tried with magic.
"Emma, no!" Regina shouted to warn the saviour, but she had already tried to blast her way out of the vault. The magic was useless and it bounced back at Emma, but Regina pushed her out of the way, their previous arguments forgotten, the magic hit the former Evil Queen hard and sent her across the room into the back wall. She groaned on impact.
Emma's eyes widened at the scene in front of her. What just happened? As soon as she regained her composure, she rushed to Regina's side. She had a small gash on her head and she was unconscious, but as far as Emma could tell, she was okay.
Regina only took a few minutes to regain consciousness. At first her vision was slightly blurry, but she eventually realised, she was in her vault with the saviour and the recent events replayed in her head. She didn't make a move to try and get up, but she moved from Emma's arms to sit against the wall.
"You can open my vault from the outside with magic, unless I really don't want people snooping, but you can't from the inside because I thought the doors were magically blocked and your magic bouncing back at you proofed it." She said rather coldly, their previous conversation coming back to her.
Regina pressed her hand on the wall to get up, Emma grabbed her other arm and helped her to her feet, despite her protests that she didn't need help.
"I need you to do some mirror magic, remember how you did it before to check on Ariel and her prince? Just do it exactly the same." She started to regain her balance and walked over to her mirror with Emma.
Emma remembered everything she did last time when Regina showed her mirror magic and she followed the steps from memory. A blurry image appeared, as if by magic on the mirror, but it soon cleared to show a blast of ice blocking the door of the vault. The two ice queens were close by, but were too busy fighting to realise the real damage that their actions were creating.
"What do we do? Is there a potion or spell that can get us out of here?" Emma asked.
"Now that we can see the doors, I can judge when I can leave and I can just do the same as when Marian almost got killed by the monster. I just need to know that snow and ice out there won't freeze me before I can free my vault."
"Listen, Regina about before. I don't want to sway my guilt or to make you feel any worse. I was just looking for you to be my friend." Regina's eyes widened and she raised an eyebrow. "I know, crazy right? But I have Henry and I have my family, but they can't always understand me. It just feels like we can relate, more than anyone else I know." She paused, letting everything she'd said sink in.
"I suppose we can and what's done is done? Looks like we can get out of here." She said and without giving Emma the chance to respond, she disappeared in a cloud of purple smoke.
She watched the mayor look over her shoulder to check that the other queens were occupied further away, so that she could defrost her vault doors. The former evil queen raised her hands in front of the iced doors and focused. Emma watched closely as cracks formed in the ice until the ice barrier broke all together. Emma was free and the saviour and mayor were on better terms. They used their magic together to stop the snow queen and help Elsa to try to find her lost sister, Anna. Regina even took Emma under her wing and helped her develop her magic.