Pair of scissortail dartfish problems?

Hey there. Situation: Got 2 scissortails about 4 months ago from LA. Actually 3 but one was DOA. Anyways, I quarantined the 2 for 12 weeks in a 10 gallon. While in the 10 gallon I noticed that 1 seemed to be more dominant than the other and seem to not let the other get food. I put them into the DT...at first they both came out together during feeding...as of the past 2 weeks it seems like the one only comes out of the den and aggressively eats and then he darts back into the burrow and seems to maybe rough the other one up a bit. Is this actually happening I dont know. Either way the one goes for the food and the other one sits back in the den with just its head popping out. I am worried that they are fighting...however...however I have heard that with scissortail dartfish you have a more dominant one and so forth. The other one does look skinner and definitely has a more "bowed" look but good coloration. While the other one looks much fatter. The other one does not necessarily look like its in ill health...just a bit slimmer it seems. Its hard to tell with Darts because they already look skinny IMO. ALSO...the fish share there den with a fire shrimp....I dont know if that makes a difference just giving you guys info. The fish are in a 90 gallon reef tank and are the ONLY fish in there btw. I have had these fish a total of like I said about 5 months now....I would have thought that if the one was not eating it would have been dead by now....so am I just over reacting or do I need to seperate the two. I will also say...the more dominant one eats when I feed him...however when I leave the room the other one comes out after a few minutes with the dominant one and hangs close to the other guy and NO FIGHTING, and I try to feed it and BOTH of them want nothing to do with the food. I will also say that the only time I notice what I MAY consider fighting of the dominant one is during feed time...that is it.