Artist’s description from DA:

Sunburst and Thorax had met multiple times at big events and had hung out on occassion together with mutual friends but they had never got the time to talk just the two of them. It wasn’t because of dissinterest on Sunburst’s part, far from it, he was absolutely fascinated and awestruck by the changeling. He was so curious about how they lived and how their magic worked but he was just too scared to ever ask, feeling like it would be incredibly rude and insensetive… and also talking to ponies was kinda intimidating overall. He vented his social awkwardness to Starlight one night and so Starlight started to plot how she could help out her friend.

Luck would have it that Thorax came to her one day and asked for some help with a magical artifact that one of his drones had managed to dig up and Starlight insisted that the best one to ask for help studying it would be Sunburst! The yellow stallion jumped at the chance to get to go to the changeling kingdom and soon found himself as the research partner to the prince himself.

Thorax and Sunburst enjoyed working together, so much so that Thorax found more things for them to study and work on together so that Sunburst would stay longer. Sunburst always agreed even if the task itself seemed trivial since he also wanted to stay longer but couldn’t quite seem to just outright say it.

After some time though Sunburst finally felt comfortable enough around Thorax to actually ask if it would be alright for him to study how changelings worked since there was little to no books on the subject in any of the many pony archives he had visited. Thorax of course agreed and was delighted to help.

The two grew closer as time went on and both started to feel something more for one another, but both of course being too shy to actually say or insinuate anything. It wasn’t untill Sunburst in all his awkward glory accidentally said “I love you” when he intended to say “I love working with you” that they both got the courage to confess to one another. They have been dorky boyfriends ever since.

Sunburst decided to move in permanently into the changeling hive and resigned as royal wizard of the Crystal Empire. Instead he now works as a proffesor, writing books on changelings and other strange magical phenomenon, and travels around Equestria giving lectures. He also helps Thorax with running the hive. Thorax does his best to try and rebuild the changelings image and to keep the few subjects he has happy and thriving.

1: Thorax and Sunburst being emotional goofers. Reformed changelings involuntarily share strong emotions of those around them especially if the one they get the emotions from is someone close to them. So when Sunburst got all sappy and proud about a letter he got from his daughter Marigold, Thorax started crying along with him.

2: Some sugar coated kisses.

3: Thorax freaking out about being in charge with Sunburst comforting him and giving advice. Thorax isn’t exactly the best leader as he is kind of awkward and has a hard time with the whole “demanding respect” thing, but he genuinly cares and tries his best.

In this particular situation Thorax is worried about the longevity of their hive and how they will be able to expand without being able to reproduce like they did before.

4: Random cuddles. They cuddle a lot as it is how Thorax recharges and gets his energy. But also because it’s cozy and nice to just be close to one another.

5: Thorax showing of his powers to an excited Sunburst taking notes.

6: The whole family! Sunburst and Thorax together with Marigold and their newly hatched surprise grubs.

Changelings don’t reproduce like most other creatures. When they were all life sucking nightmares they used other creatures as hosts to magically inject their eggs into. The whole process is highly uncomfortable for the host and is in some cases deadly. The resulting grubs are also always born as the black cursed kind of changeling. So as far as the reformed changelings knew they had no way of reproducing.

Until Thorax all of a sudden laid eggs that is.

Reformed changelings reproduce via love (cheesy I know). When they have a partner that they love a whole lot and there is enough emotion-food available to sustain themselves and their eggs changelings can spontaniously become pregnant. If the conditions for the pregnancy changes too drastically the eggs will stop their development and wait for the right conditions to occur again. The grubs from these eggs will always be the colorful and sparkly kind of changeling even if one of the parents isn’t a changeling at all.

This discovery was both highly startling, exciting and a relief for everyone involved when Sunburst and Thorax suddenly realised they had 7 kids to care for.

Twilight, Starlight and Sunburst worked together on a spell that would prevent further surpise clutches.