They love this bed because Mama's in it, but when Mama leaves and they're half asleep they're content to snuggle close to each other, enjoying the warmth and love of someone who is not Mama, a beautiful symbiosis of mutual need.
I think life is like this. As they grow I will become less physically present for them, until I will be one day not at all, and in all these moments they will turn to each other and maybe not cuddle but something. That is the reason to have brothers.
Also, it should be noted that our older child stays in his bed all night. Praise to Harvey.