Excess Hormones?

It is just the older piggy trying to establish his/her dominance. It should go away once the dominance is established, can't tell you exactly how long that will take. =)

Have a look at this part of the Social Life page https://www.cavyspirit.com/sociallife.htm#Introductions - it lists all the introduction behaviours that are perfectly normal and nothing to worry about (of which humping is definitely one!). Should help reassure you as I know it can all seem quite frantic!

As for biting - have a look at this page for possible reasons https://www.cavyspirit.com/biting.htm. With him being quite young, he may still be in the 'if you don't know hat it is, nibble it' phase, or perhaps you keep handling veggies just before handling him and he's a bit confused about which is food and which is finger. But there's plenty of good advice on making sure he feels secure when you're handling him and also possibilities like him having mites which make guinea pigs reluctant to be handled. Good luck!

My pigs both bit me when they were new. I think I got it once or twice from each pig. Once was just poor thinking on my part. I cut up a nectarine and my fingers were covered in the juice. I then tried to feed a piece to my pig and he mistook my finger for the fruit. Once they were older they stopped biting, even when roughhoused a bit too much by the kids. They are very gentle.

As they got older they also stopped peeing and pooping on our laps - thank goodness!!!

ok thats great!!! thanks everyone!!!!