How good is she at hiding her emotions? Is there any tells that those close to her pick up on?
so i took a little while to answer this just because i'm really still building up the rose siblings and i wanted to have a clear idea of what i wanted to say, because this really is an excellent question.
the truth is that ellie-may lies somewhere between terrible at concealing how she truly feels and an absolute master at preserving a sense of 'positivity' when she isn't feeling particularly joyful, because she feels she must.
on the one hand, ellie is an open book. she doesn't like lying to people, and she doesn't really have a problem with people being able to read her. she doesn't take any pride in being an 'inpenetrable fortress' or anything like that; if anything, she tries to be direct because, as a woman growing up in the 80's, it's hard enough to be taken seriously as is. dancing around the topic of how she feels and shying away from it would only add to the assumption that she's too meek to really know what she wants / expects from people. she also, moving away from the boring political stuff, just likes to connect with people? it's easier to make friends if you convey yourself plainly and let people in, and again, ellie has absolutely no problem with people knowing what she really thinks / feels.
that being said? she does feel some amount of pressure to maintain an air of positivity. i should note that said pressure is entirely within her own head and most of it stems from a desire to help the people she loves. falsely, sometimes she believes that the best way to support somebody who's faltering emotionally is to display unyielding optimism and be a 'source of light' for them; not to try and fix them, but simply to show them that happiness is attainable, i guess? that there's always a bright side to look on? there's also the fact that at this point in her life, ellie is known for her cheery personality. when she goes through her bouts of depression, or when she feels weak and cynical and moody, there's a certain compulsion to hide it because it doesn't suit the ellie that people have come to know, and she ultimately prioritises other people's comfort / happiness over her own emotions.
i suppose the eeriest part of all this is that she doesn't really have any tells. if she really wants to conceal how she feels from you, you will never know she's being dishonest. she can be that good at keeping her true feelings under wraps if she deems it necessary..
tl;dr: she's somewhere between 'that's pointless to do, feel my Wrath' and 'you will never know the Truth'..