Go to Simulation Room

For sake of the story, let's say that simulation room can run few separate simulations at a time

In the end, you decided to go check the simulation room. As you were making your way there, you saw Mordred going in the same direction.

"Hey Master! Going to the simulation room? I'm about to go there myself so feel free to come by, and see me kicking some ass! I'm gonna show you I'm better than that pathetic version of me you saw serving Lion King in that singularity once! It pisses me off I couldn't be there to beat some sense into my other self." The blonde tomboy knight said with her usual grin when she noticed you

Despite being known as the knight of betrayal, you didn't really consider Mordred untrustworthy, even if she was a bit hotheaded and short-tempered, you had no doubt about her being loyal to you as her master, even if she probably would have trouble admitting it out loud.

You replied that you will think about coming to check on her training...

"What, you got anything better to do?" Mordred tried to sound annoyed, but there was also hint of disappointment in her tone

"Well anyway, I better get my ass over there before someone takes my spot in the simulator! See ya Master!" Mordred said before you could reply to her earlier question and quickly went ahead towards the simulation room.

Just as Mordred disappeared from your sight, you felt a presence appearing behind you.

"Master! Have you seen a saber coming this way? I'm sure I saw one of them just now going in this direction!" Said a familiar voice, quite obviously belonging to Mysterious Heroine X.

She presumably meant Mordred... for whatever reason Mysterious Heroine X had a big grudge against all saber class servants, especially ones with particular faces... similar to her own in fact. She certainly was a bit unpredictable and random one... but seemed to mean well despite that.

"Uhhh... no." You decided to lie, it wouldn't be good if MHX decided to start bothering Mordred all of a sudden, especially given her similarity to certain someone...

"Damn, she must have realized I was there, at times like these I wish I had Presence Concealment skill like the Assassin class." The girl in a blue hat said with annoyance.

She technically was an assassin even if she didn't have that skill... but you didn't want to start an argument with her about that.

"I will be on my way then! That saber couldn't have escaped far!" Mysterious Heroine said as she ran off somewhere... perhaps following her and making sure she doesn't cause trouble would be a good idea?

For the moment however you decided to just get on your way towards the simulator room, finally arriving to the door leading to it without further interruptions. Just as you were about to enter however...

"¡Hola! Are you going to the simulator Master?" A cheerful energetic female voice sounded behind you, there was only one person it could belong to, and sure enough, once you turned around you saw Quetzalcoatl, the tall lucha-loving goddess herself.

Despite her goddess status she was probably one of the nicest servants in Chaldea... although she could be rather terrifying when angered, fortunately she wasn't usually angry at you.

"Yeah, are you going there too?" You asked

"¡Si! I need to keep up my lucha skills! Would you like to train with me master? It's always better to do it against a real opponent! Don't worry, big sis will take it easy on you, yes!" The tall enthusiastic goddess said, and it didn't seem like she was going to give up easily...

You remembered last time Quetzalcoatl got you to practice with her... your bones hurt for entire next week. On top of that during practice you were having hard time not staring at her open-toed shoes, which were always showing you the sexy long toes of the goddess adorned with green toenail polish... nonetheless it wasn't time to think about that now.

Perhaps you could use Mordred's earlier request to watch her training to excuse yourself though? Eventually you could follow your earlier hunch about following Mysterious Heroine X from causing any trouble in Chaldea...