Oh, Helen. Helen, Helen, Helen. Though we start out with friendly feelings for the younger Schlegel sister, it's impossible not to get exasperated by her headstrong behavior as the novel progresses. We have to give Margaret mad props for putting up with this pushy little sister; while Helen's certainly funny and lovable, she's also incredibly self-centered and self-indulgent at times. She, like Margaret, is independent, liberal, and extremely intelligent (not to mention argumentative), but unlike her older sibling, she doesn't exactly believe in the practical workings of the world. She's prettier and more charming than Margaret, and these things make her more popular in general…and they also allow her to drift through life in a kind of idealistic bubble. Helen's got money, looks, and brains, and all of this put together makes her a formidable young woman.
Helen, though she doesn't realize it, is spoiled in a very special way. Though she thinks she has the world figured all out, and that she's above petty concerns like money, she doesn't fully comprehend what Margaret increasingly does – that money is what enables her liberal, idealistic lifestyle. She's always spouting off poetic, abstract ideas about things like poverty and social injustice, but she doesn't see the irony here: Helen herself is rich, and she can never understand what it's like to be poor. For this reason, all of her philosophizing never really comes to anything, and when it comes down to actually helping people – the Basts – she proves to be a complete failure. If anything, Helen inadvertently causes their ruin, though she never fully understands that.
But Helen isn't all bad – she means well, after all. She's like that friend we all have who's totally involved with herself all the time; there's nothing malicious about it or anything, but she just can't really see outside the boundaries of the life she's always lived. Helen attempts to escape the repercussions of her decisions by fleeing England and gallivanting about Germany, which is posed as a kind of more liberal space. But, in the end, she can't stay away from her real home forever. Even though she's half German, her place is ultimately in England, at Howards End, with her family – Margaret, Henry, her baby, and even the difficult Tibby.
By the end of the novel, Helen has softened a little and, like everyone else, the tragedy that the Wilcox-Schlegel family has come through together has forced her to grow up and see the world more clearly. The interference of real life with her philosophical ideals seems to have finally taught her a lesson, the hard way.