Where did My new spells come from and other off level up ques

When you level up and get some more spells
In a fast campaign, my players would level up most sessions and in later game, lots of downtime and yearly campaign turns. Sorta of training/experience montage scenes.

My players asked for slower advancement which also has ended up with players between zero to 2nd level. A zero-level person will level up to one quickly having adventures rather than the slow 4 years most people take. Players want to enjoy and learn abilities more before advancing which I like. I have felt this in D&D5 with very rapid advancement was easy. 

People have lots of children in my games. Pendragon in the 80s was an influence.

These are for some level-up colour or used like carousing or downtime. You could play them out or take note of enemies possibly gained or other plots and allegiances.

Usually, I encourage wizards to trade and robe other wizards but also in my game, you get some spells at every level so this is a lazy source of ideas for researching your new spells off-scene. Maybe could be player backgrounds?

d12 Where did my new Priest miracles come from?
1 Went on pilgrimage and met a living saint
2 Went on a pilgrimage and had a vision 
3 Negotiated a just settlement to a lengthy dispute between factions
4 Recruited new acolytes to the faith proselytizing and helping desperate and needy
5 Helped protect pilgrims on the frontier from bandits and other enemies
6 Reclaimed a holy sight from enemies and helped build a shrine 

7 Helped hunt a dangerous unlawful magician terrorising a community
8 Went on a crusade for the climax of a mighty siege against the enemy
9 Helped stamp out a sinister cult on the frontier

10 Cleansed graves and tombs of dangerous undead 
11 Helped to scourge a dangerous heresy that sprung up like wildfire
12 Studied holy texts and wrote an impressive doctrinal essay

d12 Where did my new Rogue skills come from?
1 Hours of training in the secret guild school hidden from the outside world
2 Serve a specialist master as a journeyman to learn new rare expertise
3 A secret army of sewer beggars teach you skills for the coming troubles
4 Had to protect a friendly contact's business from an upstart gang
5 Worked with a team of charlatans to make a fortune on the market by sabotage
6 Serve a guild master who trained you in rare techniques 
7 Found manuals of techniques in the guild library
8 Recruited to purge a castle of spies and gained a noble ear
9 Ran wild with a gang of lawless rebels on the run from unjust authorities
10 Helped merchants smuggle tax-free goods across the region
11 Faught a vicious gang war with a rival organisation
12 Power struggle over the guild itself and you were on one faction

d12 Where did my new Warriors skills come from?
1 Training with austere dedication without pleasure
2 Study of combat manuals in a fighting guild library or noble collection
2 Trained with guild experts and instructed lower-level guild members
3 Spent time drunkenly brawling and dueling its a wonder you lived
4 Recruited into millitary unit for a brief campaign
5 Recruited by the guild to lead an expedition or mission
6 Battled for fame and glory in combat sports 
7 Served as a guard protecting clients and property from enemies
8 Befriened by an older wiser warrior and fought in a siege that killed the friend
9 Studied techniques of various exotic fighting styles through observation
10 Learned new techniques from a wise old hermit instructor in a hidden place
11 Spent time with faerie or magic folk and learned their secret techniques
12 Wild dreams of your past life when you were at a higher level that is an inspiration to you. Perhaps some spirit, ghost or your oath patron influenced your dreams

d12 Where did my new Wizard spells come from?
1 Dangerous experiments based on fragments finally paid off
2 Accessed an ancient library and found some ideas

3 Got a journeyman spell book from a school or guild that insists you join them

4 Got help from another wizard's apprentices to get what you needed in secret

5 From inscriptions, fragments of text, old books and dead languages

6 Enrolled in a university course to access spell library stacks

7 Traded in secret with another wizard you met by chance

8 Robbed a wizard with some friends and you took all the occult documents

9 Dueled a wizard who refused to share research and took what you needed (Did you finish them? Use a disguise?)

10 Older wizards of a secret society gives spells for your deeds that align with their goals

11 Found blasphemous scrolls of prehuman wizards from the second age when monster kings ruled the earth and humans were slaves (or anything worse you dream up)

12 Free tuition at a secret diabolic magic school run by imps and devils from inside a cupboard door gateway that disappeared later. Pick up a lawful or evil oath while your in hell

d12 Where did my new Bard powers come from?
1 Trained under a master of a style new to you
2 Went to a song festival and met bards of the kingdom
3 Went on a busking tour of markets listening for gossip
4 Went on tour performing in taverns and rich halls
5 Studied at a new school operated by a famous bard
6 Served in the court of a noble as a servant, entertainer and spy
7 Worked in a castle during an important conference to keep the peace
8 Recruited by city or crown to spread the news as a crier over the land
9 Carried important secret messages while travelling 
10 Sent to negotiate the release of a hostage 
11 Had musical battles with other bards to improve your fame
12 Briefly important people wanted you to play for them to see one of your famous performances

d12 Where did my new Druid miracles come from?
1 Inspired by living like a hermit in the wilderness rambling in nature
2 Lived as an animal among others of that species and made a new family
3 Trained by a druidic circle and in turn helped instruct aspirants to the faith
4 Helping plants and animals over an area to survive and multiply
5 Helped druid circle create magical guardians of holy places
6 Helped druid circle summon elemental beings to perform labour
7 Removed a feral species from a wilderness out of balance with nature

8 Found a long lost holy grotto and rewarded by land spirits
9 Helped a great festival procession of sacred sites and a climax of monolith erecting
10 Spent time in fairyland with supernatural lovers
11 Help druids create new hybrid monsters or giant animals to destroy an ancient enemy
12 Met a nature divinity on a seasonal procession and comune with them briefly

d12 Where did my new Savant skills come from?
1 Studies with a secret order in a hidden monastery
2 Found an old master who taught you secret techniques
3 Involved in the family feud of two family schools while learning a new skill
4 Got into constant duels with increasingly dangerous opponents
5 Defended villagers from common criminals and taught them to fight
6 Went wandering to encounter new techniques in other lands
7 Entered a grand tournament of different fighting styles
8 Protected an isolated monastery or school from monsters
9 Avenged a great master defeated with trickery by a coward
10 Pestered a master to study under them until they attacked you and you put up an adequate defence and were accepted
11 Studied under a mysterious master who was really sent to evaluate then kill you all along
12 Taught by supernatural hidden peoples who judged you worthy like spirit folk or ghost

d12 Where did my new Sorcery powers come from?
1 Almost died from an overdose or drinking and met mysterious beings trying to talk to you
2 Went into a bone-chilling fever fits and had visions of your supernatural power source 
3 Went to a festival where sorcerers were free to show off and hang out and party
4 Licked a rare salamander or toad and saw ultimate reality of your power source
5 Was involved in a cult promising to expand your mind and it ended in burned buildings and tears
6 Captured by zealots who tortured you until you got a free hand and ungagged and killed them all with your new awakened power
7 A messenger of your power source comes to inform you of new ways to draw on the magic energy
8 Hung out with a witch cult and learned lots of solid technique 
9 Met a sorcerer lover and both your powers grew together
10 Almost died doing something stupid to impress people and your power source patron saved you so it could renew your vows
11 Had visions of your first supernatural ancestor and feel empowered
12 You were taken to the source directly to communicate with its mighty spirit