Character Crunch: Optional Hybrid Rules

You probably already about the half-elves and half-orcs. They are two of the standard races in 5th edition D & D. You probably are also aware of past editions either arbitrarily deciding that only humans can breed with other races OR attempting to do a few half-breeds. Or y'know...

...the problematic and troubling nature of "mongrelfolk". This implies that the gods don't want races to intermingle. It implies that cross-breeding between the races is wrong. And, in my setting and maybe yours, that doesn't sit right with me.

In my setting, the goddess of love, Kleeona, is also the goddess of love children. She is the mother who loves all children, regardless of their parentage, and encourages all love.When peoples of two races in Sublanarya wish to have a child, it is to Kleeona they pray. And, without magical aid, the following races are capable of interbreeding:

Dwarves, elves, gnomes, halflings, humans, orcs, and merfolk.

This article has custom rules for creating hybrids between two of these races but you can also use it as a guideline to make hybrids of more than two of any race. I also am including optional rules on how to create Aasamir and Tieflings of any race.

IMPORTANT NOTES: I would consider these optional or variant rules.

To create a hybrid you take abilities from each of their parents to create a combination. For example, a dwelf is half-dwarf and half-elf. They combine the features of both races. This creates combos that, in many respects, unbalanced. Definitely make sure this is alright with your GM and players before making a character with these rules. I'm sure some of these combos break the game, so lemme know if they do! I can already see some problematic combos. My advice if that happens? Get your GM to take a look at the two races you wanna combine and work together to make something that is more balanced. Thanks and enjoy.

All Hybrids have the following features:

Age: Your character's age and maturity is probably determined by one of their parents or a median between them.
Alignment: Hybrids can have any alignment but are often influenced by their heritage.
Size: All hybrids are Medium size unless one of their parents is a gnome, goblin, or halfling. In the case, you may choose to be Small or Medium size. If both of your parents are a combination of gnome, goblin and halfling, you are Small.
Speed: Your speed is usually 30 unless one of your parents is a dwarf or if you choose to be Small, your speed is 25.
Hybrid Ability: You gain a +1 to one ability score of your choice.
Hybrid Linguist: You may be proficient in speaking, reading and writing in the languages of one or both of your parent's racial languages.
Hybrid Versatility: You gain proficiency in one skills or tool proficiency of your choice.
Parent Races: You gain additional abilities by picking two of the following options. The exceptions, typically, are half-orc and half-human and half-human and half-elves.

Half-Dwarves always get +1 to their Constitution ability score, Darkvision, are not slowed while wearing heavy armor, and have advantage on saving throws against poison and resistance to poison damage.

They may choose to forgo Hybrid Versatility for proficiency with the battleaxe, handaxe, Light Hammer, and Warhammer.

Half-Elves (and half-half-elves) always get +1 to their Dexterity ability score, darkvision, and advantage on saving throws against being charmed, and magic can’t put them to sleep.

They may choose to forgo Hybrid Versatility for proficiency with the short sword, long sword, long bow, and short bow.

Half-Gnomes always get +1 to their Intelligence ability score, Darkvision, advantage on saving throws against Intelligence, Wisdom, and Charisma saving throws against magic and proficiency with a toolset or the minor illusion cantrip (use Intelligence as their spellcasting ability for it).

Half-Goblinoidss always get dark vision.

Half-Bugbears get a +1 to their Strength ability score, and they count as one size larger when determining their carrying capacity and the weight they can push, drag, or lift, and if they surprise a creature and hit it with an attack on their first turn in combat, the attack deals an extra 2d6 damage to it (you regain this ability on a short rest).

Half-Goblins get a +1 to their Dexterity ability score, the ability to take the Disengage or Hide action as a bonus action, and when they damage a creature with an attack or a spell and the creature's size is larger than yours, they can cause the attack or spell to deal additional damage to the creature. The damage is equal to they level (Once they use this trait, they can't use it again until they finish a long rest).

Half-Hobgoblins get a +1 to their Constitution ability score, proficiency with two martial weapons of their choice and with light armor, and when they miss with attack roll or fail an ability check or a saving throw, they may choose to instead gain a bonus to the roll equal to the number of allies they can see within 30 feet (max. bonus of +5) (Once they use this trait, they can't use it again until you finish a long rest).

Half-Halflings always get +1 to their Dexterity ability score, the ability to reroll 1s on attack rolls, ability checks, or saving throws (they must use the new result even if it is a 1 and you regain this ability after taking a short rest), and advantage on saving throws against being frightened.

If they are Small, they may also move through the space of any creature that is of a size larger or more.

Half-Humans always get a +1 to two ability score of your choice and a skill. Or they may choose to get a +1 to all ability scores.

Half-Orcs (and half-half-orcs) always get a +1 to their Strength ability score, dark vision, when they are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead (they can’t use this feature again until they finish a long rest), and when they score a critical hit with a melee weapon attack, they can reroll one of the weapon’s damage dice one additional time and add it to the extra damage of the critical hit.

Half-Merfolk always get a +1 to their Dexterity ability score, dark vision, can breath air or water, have a swim speed that is 2/3 of their walking speed (min. 20), and have a resistance to cold damage and can ignore any of the drawbacks caused by a deep, underwater environment.

Now, for some examples:

Let's make a dwelf (half-dwarf, half-human) for a STR-based melee Fighter.

Standard Array: 15 , 14, 13, 12, 10, 8
Str 15 Dex 12 Con 14 Wis 13 Int 10 Cha 8
Size: You are Medium.
Speed: Your speed is 25.
Hybrid Ability: Let's give him a +1 to Strength.
Hybrid Linguist: He is proficient in Dwarven and Common.
Hybrid Versatility: Let's give him Perception proficiency.
Parent Races:
Half-Dwarf: +1 to his Constitution ability score, darkvision, not slowed while wearing heavy armor, and have advantage on saving throws against poison and resistance to poison damage.
Half-Human: +1 to two ability scores and a skill? Let's give him a +1 to Constitution and a +1 to Wisdom.
Final Array: Str 16 Dex 12 Con 14 Wis 14 Int 10 Cha 8

Now, how about a elf-orc (half-orc and half-elf). Let's make her a ranger.
Standard Array: 15 , 14, 13, 12, 10, 8
Str 13 Dex 15 Con 14 Wis 12 Int 8 Cha 10
Size: You are Medium.
Speed: Your speed is 30.
Hybrid Ability: Let's give her a +2 to Wisdom.
Hybrid Linguist: She is proficient in Elf, Orc and Common.
Hybrid Versatility: Let's give her Stealth proficiency.
Parent Races: 
Half-Elves +1 to their Dexterity ability score, darkvision, and advantage on saving throws against being charmed, and magic can’t put them to sleep.
Half-Orcs get a +1 to their Strength ability score, dark vision, when they are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead (they can’t use this feature again until they finish a long rest), and when they score a critical hit with a melee weapon attack, they can reroll one of the weapon’s damage dice one additional time and add it to the extra damage of the critical hit.
Final Array: Str 14 Dex 16 Con 14 Wis 14 Int 10 Cha 8
There are also name's for hybrids.

All half-humans are called "half" and then the other parent. A half-goblin is half-goblin and half-human.

Here are some examples of other combinations: Elflings (half-elf and half-halfling), Dwelf (half-dwarf and half-elf), Gnelf (half-elf and half-gnome), Dwarfling (half-dwarf and half-halfling), Dwome (half-dwarf and half-gnome), Gnome-ling (half-gnome and half-halfling), Elf-Orc (half-elf and half-orc), Orcling, (half-orc and half-halfling) and Gnorc (half-orc and half-gnome).

Merfolk hybrids usually attach "mer" the race of their other parent. Ex. Mer-Elf (half-merfolk and half-elf).

Goblinoid hybrids usually are, for a call-back, called "Mongrelfolk".

I also have rules for non-human tiefling and aasamir using the hybrid rules. You treat aasamir and tiefling as parent races with the follow traits.

Tieflings always have a +1 to Charisma, Darkvision, resistance to fire damage, and can use Thaumaturgy (Charisma is their spellcasting ability for it).

Aasamir always have a +1 to Charisma, Darkvision, resistance to necrotic and radiant damage, you can touch a creature and cause it to regain a number of hit points equal to your level (you regain this ability after a long rest) and know the Light cantrip (Charisma is their spellcasting ability for it).