Companions
An NPC under a PCs command can take the dash, disengage, or dodge action without being directed by a PC (no action required). An NPC who becomes an companion may be commanded per DM discretion as a bonus action. Most companions must be paid per day or offered a share of the loot, but some will follow you out of sheer loyalty. Using powerful companions may reduce the total experience points awarded by the encounter, at DM's discretion.
Familiars
A Familiar can take the dash, disengage, or dodge action without being directed by a PC (no action required). If a being submits to you and becomes your familiar of it's own free will, it can be treated as a Pact of the Chain familiar with Investment of the Chain Master applied (meaning it can be instructed to attack as a bonus action). This bond counts as a magical item attunement, as the user is attuned to the ethereal chain which links them with their new familiar. The max CR of a familiar gained in this manner is 1/4 your character level. A higher CR creature will simply never submit to you to that degree, and will count as a companion (see above) instead.
Mounts
A Mount can take the dash, disengage, or dodge action without being directed by a PC (no action required). In addition to RAW, a mount can, as a bonus action, be commanded to attack. However, this requires an animal handling check equal to 12 + the CR of the creature. A mount will simply fail any action it has no instinct to perform and/or has not been trained in. A mount typically will not lay down it's life for it's rider, but may be persuaded to take calculated risks once trust has been established.
