You don’t need to eat, drink, or breath. You are a leather book, so you AC is 11 and you do not add DEX to your AC. For spell casting, you have a voice for Verbal and can manipulate your pages for somatic, and you are considered a Spell Focus for yourself and whoever is holding you.

You have advantage on saving throws against being poisoned, and you have resistance to poison damage.

You can be upgraded to have an AC of 12 by finding a master leatherworker who can create a harder cover for you. Absorbing the new cover takes a long rest.

When you take a long rest, you must spend at least six hours in an inactive, motionless state, rather than sleeping. In this state, you appear inert, but it doesn't render you unconscious, and you can hear and see as normal. 

If an effect would cause you to sleep, it forces you into an inert state instead. Spells and abilities like Dream, that rely on you being asleep, have no effect on you.

You have Disadvantage on Dex Saving Throws. You are considered Prone when you aren’t carried and just left on the ground. When you remain motionless and do no speak, you are indistinguishable from any other large, leather bound book.

You are a "humanoid" for all targeting purposes. Healing spells repair you. Potions are absorbed by your pages and fix your binding. 

At the end of the hour you spend attuning to a magic item, the item disappears and becomes an intricate drawing on your pages. You or your carrier gain the approximate benefits of the item's ability. Your carrier cannot gain this benefit if it would result in them benefiting from more attunement than they are allowed. 

You can speak, read, and write Common and one other language of your choice.

Your bookmark is a ribbon approximately 15 inches long. You can use it to grasp small objects such as pens for writing and pebbles for throwing at anyone you would like to annoy. This Ribbon, where tough to tear, is not quite strong enough for any attacks it does to cause damage.

Given a minute, you can tie yourself to an object or piece of clothing. When tied to something in this manor, you have disadvantage on any concentration or dexterity based checks. You can undo the knot as an action. Someone else can undo the knot with a DC 13 Slight of Hand check or a DC 15 Athletics check. 

Your size is Tiny

Your base walking speed is 5

Your Intelligence score increases by 2.