So since i've seen that for some people selene's character is very confusing because she seems to contradict herself I wanted to try explain it to you atleast how i understood it. Also I'm not going to start any unecessary discussions in the comments(most people here will know which user I mean by that lol) So let's start with her past and what caused her actions: She lived a 400 years ago to the time of the dragon king festival(but did not participate in it:chapter 3) and fled to guiltina because of acnologia like all the other dragon gods.In guiltina she got attacked by humans because of the dragon who attacked elefseria's guild(again humans putting all dragons into one pot) and so she defended herself and killed those who were after her life. The thing is she actually likes humans despite thinking that they are stupid creatures because she sees parallels between dragon and humans. This is why she wants to live as a human because it will give her the peaceful life that she can't have as a dragon god.
Now what is selene's goal and how did she try to reach it: Selene's ultimate goal is to defeat the other dragon gods and end the age of the dragons(which is basically what she said in the very beginning to faris. The fact that she wants that to live as a human was only revealed later so still no contradiction).She went to many worlds and caused chaos or in her terms "distortion"(like awaking alderon in earthland or overflowing the magic in elentir)because this will lead to the hidden power of the world which she hoped was a weapon to defeat the other dragons(so her logic is basically threating the life of humans will cause them to use their full power against her)So now you might think this contradictes with her "killing only in self defense" statement. From her point of view it's not because the chaos that she caused was necessary to reach her goal or in other words her desperate try to survive(also we don't exactly know what happened to these worlds at the end of the day afterwards. In elentir we also didn't see her killing anyone for example. The only person we saw that she killed was george who killed her son so she had the right to to do that)
So know with her whole "entertainment talk" I'm going to interpretate the way I understood it so don't take it too seriously:This whole "I'm destroying worlds for fun" is her playing the villian(which she technically is lol)because as i reread the manga the only time she talked about entertainment as a goal is in front of team natsu. In front of faris or diabolus she revealed her true goal. Now the reason why i think she did that was to test team natsu because team natsu was able to defeat alderon which is why she took interest in them.(She did the same with diabolus in the labyrinth after she took interest in suzaku and the dragon eaters)
To sum everything up:Selene had good intentions but she used extreme actions(also i'm not justifying these actions with this post but making a understanding for why she did that and her point of view)to reach her goal and she did not hesitate to bring sacrifices or be manipulative. So her goal hasn't changed at all just the way she is trying to achieve it by working together with team natsu where she doesn't have to manipulate or threat people. For example in comparison to ultear:Ultear 's traumactic past caused her to kill many people and destroy things with the intention to reach the great world of magic to see her mother again. Selene being hunted for many years caused her to distort the worlds with the intention to kill the dragon gods and live a peaceful life. The only difference is that she does not regret her actions because for her they were necessary (also remember she is a dragon. Her thinking is different than from humans and she is slowly adapting to them)
