I remember very early on, after coming out to a close friend but quite a while before I began hormone therapy, they pondered aloud, "I wonder what you're going to be like?"

At first, I assumed this was a statement on what I would physically look like after one, two or three years of feminising hormone therapy. When I responded as such, my friend clarified, "Oh, no. Not physically."

I was a bit confused by this statement, as I just thought to myself, "I won't change." I knew I'd be happier, more comfortable in my own skin, and transitioning might affect other practical parts of my life, but the idea of my personality changing in some way seemed rather foreign.

Not that I had a problem with the idea. As far as I was concerned way too much of my personality was an awkward construct - an attempt to appear masculine resulting in a thin layer of machismo atop the person I had been decades ago when I was still too young to have built this facade.

However, I hadn't realised how much of my behaviour was manufactured in some way. Or, at least how many things - from mannerisms to the way I reacted to things - I would jettison as I began to move past the self-hating part of my life.

One of the more interesting running discussions I hear (and sometimes engage in) is theorising what percentage of our emotional responses are dictated by hormones, and what are social conditioning. Trans people who've gone through hormone therapy are in the near-unique situation to be able to observe themselves - and have their friends observe them - going through mental as well as physical changes, as their body shifts from a testosterone-dominant one to an oestrogen-dominant one, or the reverse.

But we're still affected by social conditioning, those around us, and our past. So it's impossible to empirically say "I feel this way because of the oestrogen in my system". It could just as easily be that this is a behaviour I now subconsciously feel I should, as a woman, engage in - so I do. Or it could be a behaviour I've always wanted to have, but felt too shy to admit as I spent my life trying to be 'masculine'. Most likely, it's some combination of the three.

Either way, all these began to heap up and now, as I have one of my rare moments of taking a mental 'step back' and watching myself interacting with friends in a social setting... I realise I really have changed. Enormously.

There are still things that fundamentally make me me, of course. But as people who haven't seen me for much of this year are fond of telling me, I am very different indeed. Far more so than I'd ever suspected I would be.

But one of the results of realising how much I have changed as a person in such a short space of time is being forced to re-evaluate what my brain tells me, based on my memories... of relationships.

There are friends I've lost either this past year or three. Ones I don't see any more, either by intention or happenstance. Perhaps they moved, or simply moved social groups a little. Or, in some rare cases, we simply fell 'out of friendship' a little.

I often think of people - of personalities - as being figurative arrows, weaving on flight paths that are often buffeted by things they can't see.

When we become friends with someone, it's because our arrows are, be it briefly or for a very long time, going in the same direction and at close proximity to each other. Over the years they may drift apart, or closer together again. It's how we may have long-term friends we go years without talking to, only to re-kindle the friendship at a later point and wonder.

When you're in a relationship, or an intensely close friendship, it might be that you affect each other so strongly that you correct each other's emotional courses to stay closer than you might otherwise.

But eventually, on a long enough time line, you will likely move apart.

Transitioning has, at least in my case, been a massive change of the path of my figurative arrow. It's meant I suddenly find I have little to nothing in common with friends I've had for years, and other people I had little desire to spend time with have suddenly become my closest friends in the whole world.

The fun comes when I think of friends I haven't seen, or interacted with, for enormous chunks of time.

I have to pause when I get nostalgic for a friend I haven't seen in a long time - someone I knew well but haven't seen. Especially one where I know our friendship slipping has been a direct result of my transition.

I have to remember that what I am nostalgic for is a friendship - a relationship - that existed between this person who in all likelyhood hasn't change that much... and Elissa, who is a very different person to the young man who was friends with them.

I have to remind myself that all relationships change, and what I'm experiencing is a hugely accelerated version of this, and that just "seeing a friend again" will in all likelihood not bring back the friendship I had before. That isn't to say this is a bad thing. As I've said, some of my friendships have strengthened enormously as I grow and change, just as others have lost some of their spark.

But regardless, when I get pangs of nostalgia for past relationships now, it's also coated with a profound sadness - because I know that fundamentally, I will almost never be able to recapture those same friendships.

The same is true for everyone to varying degrees, I suspect, but it's never been so clear to me than now. I catch myself laughing with girlfriends about something and then try to imagine what some friend I had years ago would think of the red-headed girl laughing with the other women in the corner of a bar as they discuss what cocktail to buy next.