Yeah I wonder if we'll get flashbacks of this evil version of Nami during the next session with Amber. and I also have to admit that when I first saw this memory with the eraser and Nami's reaction, my first thought was that she was more jealous of Nika than of Summer. Nami had to experience all this for at least 3 years and her 'bad period' could have been, as you write, getting it out of her system, quoting Nadia and Zara. Turning into a bad kid after losing contact with someone close is generally a theme in the Oceanverse so far, so far we know that it happened to Nika, Nami, Leia and Bella and I won't be surprised that if Summer shows up one day, it will also turn out that she had a period in which she turned into Winter or is even still in it