I thought that we had seen the last of Tommy Merlyn when he died at the end of Season 1; and again when he had his moment of flashback-glory toward the start of Season 3. However, today Stephen Amell teased fans with this little nugget on his facebook page:
For anyone not wanting to do the math in their head, that's episode 14 of Season 3 (if I did the math correctly, anyway!), which isn't far from the mid-season finale that airs today. Which means that Tommy fans don't have too much longer to wait before seeing the younger Merlyn return to the screen!
But how will we see Tommy in this latest round of flashbacks? I'm going to go out on a limb and say that he will not be returning from the dead, although anything is possible!
Option number one is that we will see him in Hong Kong again - but I don't think that it is likely. For one thing, it's been done already in this season, and there was a fairly conclusive ending to that mini-arc. We know that Tommy and Oliver don't meet in Hong Kong because Tommy never speaks of or alludes to it in Season 1. There is the slim possibility of a meeting followed by some kind of memory-loss drug, but I feel like this would be stretching the realms of probability just a little too far.
He could return to Hong Kong to be watched from afar by Oliver - perhaps coming in for a party trip with a little business on the side, and Oliver sees him entirely by coincidence. It could be an interesting way to show how Ollie's priorities are changing - his growing disgust at the kind of lavish playtime that he used to enjoy before the crash, his alienation from Tommy's lifestyle, etc. However, I still feel like this would be a stretch. The Hong Kong flashbacks have thus far been focused on his training, and I don't think that it would be necessary or even that useful to show something from a random Tommy interaction.
The much more likely explanation, given the return of Malcolm Merlyn, is that there will be flashbacks to his relationship with his father. Thea is currently rebuilding her relationship with Oliver (whether it is genuine or not), and Malcolm is undoubtedly going to have some issues seeing them becoming closer as brother and sister again. I have a feeling that we will start seeing more Merlyn flashbacks - to his training with the League, and the raising of his son. He has something of a second chance with Thea, and I'm sure that will bring up memories of his issues with Tommy.
We may even see Merlyn remembering Oliver's relationship with Tommy, and starting to brood over the idea that Oliver took his son away, or turned him against him. Given Malcolm's relationship with Thea now, this could really get inside his head, and convince him that Oliver is trying to do the same thing with his daughter...
The final possibility (that I can think of) relates to Laurel and her new role as Black Canary. After the mid-season finale, we'll be seeing a lot of Laurel as her super-self, and from some of the synopsis and titles released, it looks like the first few episodes after the show returns will be centered around her (and possibly Oliver finding out about her new hobby!). It wouldn't surprise me to see her working through some of her issues surrounding Tommy's death, for us to see her flashbacks to a happier time with him. After all, taking up Sara's mantle is going to get her thinking about all the things that have changed for her since Oliver's return - although it seems that she has largely gotten over Tommy's death, I would love to see more of the two of them.
However it plays out, I am happy to see Tommy return to Arrow, even in another flashback situation. I was always a fan of him as a character, and love how he is such a link between Laurel, Oliver, and Malcolm.
Edit: I wrote this before the mid-season finale, when I believed that the show would not be bringing the Lazarus Pit into play. Now, I believe that this is absolutely an option, and added it to the poll. You can read more of my thoughts on the Lazarus Pit and it's possible role here.