I don't really know how else to put it. I'll give some backstory first, but it's probably long so you can skip to the question if you want. So, Smackers is a mallard at least 7 years old who lives at our pond (about 200 feet from my front yard). My family first got him and 5 other ducks after the pond was made so I know he is quite old. 4 of the ducks were rehomed because my grandpa decided 6 was too many. The one left with Smackers died though I can't remember how and later another family member had a friend rehoming a Pekin so they took her in and let her live at the pond with him but just a few months later it seems, or maybe a year, she disappeared. That was a few years ago so Smackers has been alone since other than the wild ducks that nest there yearly. Now I got 2 ducks for myself in 2017 which turned out to be a female Mallard (Goose) and male Pekin (Chicken). I did have to separate them at times because Chicken was too large and rough for her but other than that they lived happily until 2019. I had no idea hawks would kill ducks but one got to Goose and after that Chicken was alone. So in 2020 I got Chicken a friend who was also a Pekin (Puddles). After he was big enough I let them meet, slowly. Through a fence at first and then only under supervision until they were fine together. The only thing was they were territorial over their pools so that would cause some scuffles. They had 4 but if one of them was in one pool the other would of course want that one 
Now Chicken is 4 and Puddles is 1 and earlier this year I decided to see if they would enjoy living at the pond because of course there's plenty of water and room to free range and it would give Smackers some friends and they are much too big for a hawk to carry off. So I introduced them to the pond in April and let them stay there in a kennel for two weeks. During this time Smackers would just sit by the fence and stay near that corner of the pond. So now I'll start the main story.
After letting the pekins Chicken (4) and Puddles (1) stay in the kennel at our pond for two weeks I let them out so they could have their first contact with the mallard Smackers (7ish) who already lived there. Chicken and Puddles stuck together at first and Puddles would go for Smackers if he got too close to them. But Smackers would only try to get to Chicken. If he did though he would grab Chicken by the back of the head and Puddles would rush over and chase him off Chicken and back away from them. I thought ok they're just getting things sorted out. After a week or so they were all 3 finally buddies and no one was aggressive other than the occasional bite. After about 3 months I noticed Chicken was always by himself and Puddles and Smackers were together. After a couple weeks of that I noticed Chicken and Smackers were always together but Puddles was alone and if he got too close he would be chased off by Smackers. Now I just noticed a few days ago that they're all friends again getting along just fine but I did notice Smackers being a bit hostile towards Chicken. Not chasing just if Chicken would try to eat while he was eating Smackers wouldn't let him which I've never seen them be territorial towards each other over the food before so I found that odd. Is this normal? Why are they going through phases where one of them is an outcast and the other two are all buddy buddy? Should I intervene or is this ok? The only thing I would know to do is keep Chicken and Puddles in their enclosure again but I know they really seem to enjoy the pond and Smackers enjoys not being alone so I don't want to have to do this.
Now Chicken is 4 and Puddles is 1 and earlier this year I decided to see if they would enjoy living at the pond because of course there's plenty of water and room to free range and it would give Smackers some friends and they are much too big for a hawk to carry off. So I introduced them to the pond in April and let them stay there in a kennel for two weeks. During this time Smackers would just sit by the fence and stay near that corner of the pond. So now I'll start the main story.After letting the pekins Chicken (4) and Puddles (1) stay in the kennel at our pond for two weeks I let them out so they could have their first contact with the mallard Smackers (7ish) who already lived there. Chicken and Puddles stuck together at first and Puddles would go for Smackers if he got too close to them. But Smackers would only try to get to Chicken. If he did though he would grab Chicken by the back of the head and Puddles would rush over and chase him off Chicken and back away from them. I thought ok they're just getting things sorted out. After a week or so they were all 3 finally buddies and no one was aggressive other than the occasional bite. After about 3 months I noticed Chicken was always by himself and Puddles and Smackers were together. After a couple weeks of that I noticed Chicken and Smackers were always together but Puddles was alone and if he got too close he would be chased off by Smackers. Now I just noticed a few days ago that they're all friends again getting along just fine but I did notice Smackers being a bit hostile towards Chicken. Not chasing just if Chicken would try to eat while he was eating Smackers wouldn't let him which I've never seen them be territorial towards each other over the food before so I found that odd. Is this normal? Why are they going through phases where one of them is an outcast and the other two are all buddy buddy? Should I intervene or is this ok? The only thing I would know to do is keep Chicken and Puddles in their enclosure again but I know they really seem to enjoy the pond and Smackers enjoys not being alone so I don't want to have to do this.
which is why I got Chicken a friend and luckily it turned out to be male. It has been almost 4 months since they've all 3 been together. But they did get along fine for the first 2-3 months or so? Only recently have they been acting strange like I described in the last paragraph and I don't know why 
