The 19th-century poet Hanz Joerin always carried a litany of journals not because he was a(n) (i) writer but a(n) (ii) one: when inspiration did strike, his penmanship carried such preponderance that ink would bleed through to subsequent pages, rendering them unusable.

The answer is "industrious and vigorous".

Explanation:

A hard-working, dedicated and committed individual with such a relentless and energy-free mindset implies becoming a busy individual. Big character means that you will be full of energy & enthusiasm. It was the right answer because the hint obtained from its succeeding sentence "his penguin was just so prominent," shows that poet Hanz Joerin is strong and lively in composing. Its sentence "That'd seep into succeeding pages" clearly implies it.