It is a meeting that was agreed upon in the times when they were still both human. A promise to see each other again, have a cup of something hot and talk things over the drinks. A hopelessly ancient motif, grounded in assumptions of a world long since gone, but one to which they have both held to nonetheless.
Neither of them is remotely near what they once were - the place they are meeting in is physical, as are their bodies, but neither of the two bodies holds the true seat of their thought anymore. They sit down for the cup of tea, and every impression, every bit of information gathered from their senses is transmitted at faster-than-light speeds to what their brains have become, immense machines the size of planets. They have changed more than they could ever have imagined, but throughout the process, they have been careful to keep some things constant. The change from biological cells to quantum computers has never been allowed to threaten their mutual sense of companionship, nor their love for each other.
If anything, those feelings have been enhanced. They have been carefully cultivated, spun into a delicate web of emotions, each of them strenghtening all the others. They have learned to expand their spectrum of feeling, to craft into their minds entirely new emotions of previously unimaginable kind. They have learned to work their own minds like an artist works a painting, and where humans once spoke of two main kinds of feeling - pain and pleasure - they have learnt how to create thousands of categories of feeling.
And once they mastered the art, they spent millions of years carefully building up one particular set of emotions. A set as varied and deep as the whole set of all the emotions humans of old would have termed pleasant, a set that was as fundamentally a part of them as feelings of friendship and love were of any human. A set that was spun out of the thoughts and emotions they held for each other, custom-built and tailored to reflect the whole common past they had. It was carefully synchronized to be similar in them both, so they could share with each other something that could not possibly be shared with anyone else. Nor could the set have been created without the both of them: like making love, it is a gift that each of them gave and received at the same time, making them both more whole as beings.
As they now sit together and talk, those new emotions flare to life. They watch each other's faces and bodies, seeing each other in all wavelengths of light, a spectrum indescribably broader than the capacity of ancient humans. They study each other's expressions and body language - both the carefully preserved habits of old and those created later on. No longer limited to thinking one thought at a time, each tiny little detail in the other brings to mind a hundred old memories, creates a dozen new thoughts and awakens ten new emotions. Many of those reactions are communicated to the other on a level they have chosen to leave below their conscious attention, but much of what the other feels, they would know anyway. They are joined on more levels than they ever were before, linked in a more fundamental and thorough fashion than could ever have been possible earlier.
Once they wished for an opportunity to enjoy each other's presence forever. As they talk, the starscape behind them roams, shatters and reforms, millions of years of change breaking the constellations apart and building up new ones. For minds running on such speeds as theirs, with the physical bodies as the main limiting factors, every minute that passes in the outside world carries with it ten minutes of subjective time. The bodies they have chosen for themselves never tire, never feel fatigue or hunger unless they want them to - and every now and then they do choose to feel tired, so that they can fall asleep in each other's arms, or choose to feel cold, so that they can press close for the other one's warmth.
The universe is theirs, and they have all the time in the world.