Unusual african knife activity - Pair forming maybe?

[Hendre]

so during the week i got 2 new african knives, one about 4" the other 5" (eyeballed) and the resident one (daytime is the name) nipped and chased nighttime (my darker one) for about an hour, the nipping was only done by daytime, nighttime was completely passive and still insisted on sharing the log.

That evening they started swimming around each other or near each other around the tank, with the occasional nip but nothing serious. since then they are not aggressive towards each other AT ALL and are coming out in daylight which neither did before the addition of nighttime. They still occasionally circle each other but rarely hide.

 

[Hendre]

Chilling together

whole tank shot


Here are some videos of what they did

Does anyone have any idea what they are up to? also they have a 2" pink tail and a 2.5" featherfin syno as tankmates