As Sai thinks there are really people behind her enemies, but they are not for her, they want the superpower of red and blue. Unlike blue and red tell her, their power is not limited to only learning and space, they can do very different things, but if they do that they might not able to leave on the mortal world for a lifetime. Those people behind her enemies wanted to get that power and rule the world. But to possess that power they need to find blue and red in their weak state and unfortunately for them now blue and red are in good health.
Here Red and blue already promised Sai that they will help her in her revenge. Previously blue thinks that Sai is only with them due to their superpowers. But Sai don't ask help from them in her revenge, she is using them but that only for learning new things, and what more she is trying her best for red and blue's good health and safety, So they decided that they will also try their best to make her happy.
