Story Notes:

Some stuff that's Canon to my version of the story :P feel free to do whatever but this stuff might help get the intellectual juices flowing, its my notes on what im doing so it might be a little messy but eh.

Characters -
Our story happens in the same part of the same unnamed city and as such characters from the characters list may appear in either storyline, in fact if you have read an entire storyline you may even find bits of it incorporated into the other storyline.
However it is ill advised to have the two protagonists meet once swarmed, the swarms would not get along. nor would they get along with someone modified by another swarm.

Main-
Ella - Main female protagonist
Eric- Main Male Protagonist

Secondary-

Trinity - Part time gallery assistant at a boutique art gallery in the city, she is part of the alt crowd and has blue highlights and a punk inspired fashion sense including multiple piercings.
Behaviour: Trinity is very independant and a bit of a free spirit, she goes where she likes, talks to whoever and is not shy about speaking her mind or defending her position. Generally she is a cool friend to have.
She has a good sense of humor that meshes well with Ella's wit.
Body details: pert breasts and a generally sporty pixie like look, she has mid length dark black with blue highlights in her hair and she has a few tatoos and piercings in interesting places.
Likes: Art, Music, Chatting about things with coffee
Dislikes: vapid mindless people (she calls them sheeple)
Sexual details: Straight, leaning towards bi if she could ever find the right one she probably wouldn't care too much but she only dates "boys"

Swarm-
The swarm is a swarm of beetles about the size of a thumbnail, they are black with large kinda scary looking sideways moving jaws in line with their slightly flattened body.
They move as a co-ordinated swarm when outside a host, when they have entered and become symbiotic with the host they are invisible but situate themselves throughout the body burrowing into fatty tissues.

Infection:

The bugs bite feels like being pinched quite hard before the chemicals they extrude cause numbness and heal the entry point which takes about 10 seconds.|
This makes it difficult to stealthily infect someone with a bug but there are many creative ways of doing it, its part of the challenge :D

Once a swarm has put most of its individuals within a body, that body becomes the host, the swarm once in the fatty tissues begins connecting to the hosts nervous system and puts tendrils of fibros tissue out to connect to the nerves, blood vessels and other tissues. once a critical mass of individuals is reached the host may consciously influence the swarms activities but is in return also influenced, usually with a heightened sexual desire which grows towards full on perversion and who knows from there.

The bugs are undetectable when inside the host except by various medical scans or airport scanners, they become soft and maleable partially changing thier form to resemble fatty tissues in a host so that they cannot be exposed through compression of the skin or feeling around for them.

They can be seen and felt moving around the body until they have entered the fat tissue where they become squishy instead of hard.

Bug ammounts required to affect certain changes: - effects stack
1 - can influence a persons emotions and adjust overall pleasure/pain state (untargeted)
5 - can take over voluntary movement of a host, cause hormonal and other minor bodily function changes, can effectively switch organs, limbs and various muscles on and off at will.
10 - can perform "surgery" they can modify and change body parts, can put a human into "sleep mode" where they will remain until commanded. also capable of healing major wounds and reversing aging. however all activities take around 24 hours to complete
40 - can perform complete body change, major surgery and makes anyone affected by them nearly immortal if desired as wounds and diseases ect. can be treated immediately. capable of performing minor brain surgery to elicit various changes in behavior, this is a little hit and miss though unless the user reads up on medical practices.
100 - capable of returning the dead to life, can successfully attach two or more living beings to eachother and perform cross species attachments, rejection is not a problem due to the bugs chemical excretions.

500- Hosts minimum count of bugs before they start losing control, bugs will go into a breeding mode where the host will uncontrollably seek another human to fuck thier brains out, during this process the bugs are able to make more of themselves.

1000- Maximum number of bugs a host can hold before the swarm will not make more, so your average swarm sits at 1000 +- 50 or so.

Splitting - a swarm can split if the host gives half of thier bugs to another person, this will create a new swarm, however the new swarm will recognise they are from the same "family" and remain friendly unlike with unrelated swarms.

Bug Usage: <--- updated
Bugs can be used many ways, but mainly the host wills a bug to perform an action and the bugs will do so, there are limitations however
A host can not order all bugs to leave them without falling due to bug loss, if the host tries to use too many bugs at one time they will gradually lose energy and may pass out, this puts the bugs into an automatic hide mode, bugs will hide in dark places if the host falls . bugs cannot survive for long without a host body and will only survive for a couple of days.

Bugs may be ordered only if they are within visual range of the host or the person they are inside is in visual range, bugs that cannot be seen may be ordered if they are within physical shouting distance of the host.

The longer a host has control of the swarm the more bugs they can make use of at one time, and the more situations they can exert control in. A highly experienced host may be able to control bugs through live TV broadcasts. or even over large distance using technology like transmitters ect.

Bugs may be physically ordered to move in any way the host desires, they are able to perform basic physical tasks but are limited to their physiology, they are incapable of flight. and are relatively weak and not well armored so even in the natural world they would be easy prey to rats and other creatures.

Immunity:
some people are naturally repugnant to the bugs something to do with chemicals and hormones these include - people under the age of 21, people who are going bald. and the odd random other people.
the bugs will not go near immune people and will flow around them leaving a 30cm gap they will not cross.

Modification:
The bugs excrete unique hormones and other chemicals as well as directly tamper with genetics, physical surgery and healing, as well as being able to connect and directly stimulate the nervous system including being capable of overriding a brains voluntary movement if connected to the upper spinal cord.

Other Swarms:
The swarm is able to detect other swarms, hosts and affected because of hormones and scent trails, this does not mean they instinctively know a host on sight, they have to get a whiff of hormones first so it might take a while.

The swarm is very territorial and may act aggressively to other swarms or affected without the host's being able to influence them.
Split Swarms:
Split swarms are friendly with each other but unfriendly to all others so, it is like a chain, each link is friendly with those it is linked with but no others.

Government:
the government knows of the existence of swarms and even has in the past had a captured specimen swarm but it escaped, they have a team dedicated to hunting down and eradicating swarms, they know the end results of swarm infection (or think they know) so they think they are doing the right thing by killing them off.
The government have a vaccine but its ingredients are rare and requires bugs to create so only a few people are immune to the bugs this way.