Examples of words for a 'person that makes things happen' are:
facilitator
leader
achiever
director
organizer
troublemaker
rabble-rouser
inventor
founder
creator
"Observe" means to watch something happen.
no. hopeful means that if you want something to happen, then you are hopeful that it will happen. pity means if something bad happened, it would be a pity.
Event and episode are synonyms for happening.
bale
exhibit
sqw
Obviate
invent
fake
Make changes
bisect
aggrevate