MIL was watching them last night for my birthday and James and I went on a date. She was amazed that Cody and Sophia do not fight at this age and love each other. I am not worried at all.
I think you should count your blessings
Although my kids did not fight either when DD was Sophia's age. Now DS is usually the instigator and DD comes back at him with a force. We always joke that no one will mess with DS when he is older because his little sister will beat them up.
I have 2 boys who love to fight. They love each other and look out for each other, but they have a hard time sharing!
My two don't fight often. 99% of the time they are curled up right next to each other or sitting with legs intertwined reading a book or playing a game together. They don't fight at all in front of babysitters or family. Most of the fights they do have are resolved in a minute or so without much intervention from us. .
So, consider yourself lucky!
My 2 boys love to pay with each other, and DS2 (2) adores DS1 (4). DS1 finds way to really pester him, though. So they don't really fight, but DS1 gets on DS2's nerves a lot!
I hear that about my kids a lot that because we deal with very little sib rivalry my kids aren't typical. That may be true but they are normal . We get a little bit of bickering and arguing but for the most part they treat each other respectfully and kindly. I do consider myself blessed but it has taken *a lot* of effort on my part. We'd be the luckiest people alive to have gotten 9 kiddos who naturally get along with one another !!!
I'm often hoarse at the end of the day because of talking almost constantly throughout the day with my kids (ages almost 17yrs to 13months). I work hard to keep the relationships in our home happy and healthy. It is exhausting some days but this is my job and I love it...wouldn't have it any other way . Every day isn't perfect obviously and my oldest two boys have gotten in outright brawls that are mostly good-natured fun but they don't always end well...still getting used to the ways of older boys. Dh reassures me it's fine but phew! I grew up with two rough-housing brothers and still don't get the appeal !!
I really think it's super that your little ones get along so well...no reason that can't/won't continue!!
My brother and I are a little over 3 years apart, and I have nephews that are 4 years apart. The early years were always easy. I know that my brother and I fought like cats and dogs for a really long time after. To the point where mom got fed up and said that if one killed the other, then she'd at least only have one to deal with My nephews also started off really well, but once the younger one started really getting in the older one's space, it went downhill. The older one is a very mature and patient kid, but boy, the younger one sure knows how to work his buttons.