Gretel is depicted as someone who is in love with the Nazis and fascinated with climbing the ladder of social success. The fact that she spends the family's evening with Hitler and Eva Braun trying to impress both of them would indicate this. Gretel is shown to be an embracer of Nazi ideology and one that will do anything for "another badge on the uniform." In the end, I am note sure she is really likable. She refers to Bruno as "the hopeless one." Given the fact that Bruno is extremely likable in both the nature of his character and what ends up happening to him due to his loyalty to Shmuel, I cannot see Gretel as being very likable. Gretel shows little of the human character that Bruno shows, and is willing to stand by and encourage the deliberate annihilation of millions in the name of Nazism. If we went on the idea that our judgment of characters as readers carry weight, I am not sure that Gretel can be likable as she has to be held accountable for her advocacy of Nazism and its implications upon the lives of millions.
I think that Gretel can be likable. This is because she is only a child, and she is unaware of what is happening around her. She is kept away from the Nazi world by her parents for her own good. She has been forced to move from her home in Berlin, just like Bruno. Also, she has no friends like Bruno to show her loyalty to. She gets very lonely at times, so the only people there are to influence her are the people she communicates with everyday, Kotler and Herr Liszt. She does not have much of a choice. I understand that she is easily influenced but many children look up to their fathers and do not want to disobey them. Gretel is justified. Bruno is just a younger brother. All brothers have something bad to say about their sisters, who likes their siblings? We have not heard the story from Gretel's point of view yet. She has her own feelings too. Just because she has been influenced by her Father does not justify anything. She puts up the posters of the country because she has patriotism in herself. She wants to show that she is mature and old enough to understand what is happening.